Alpha-1 adrenergic receptor
Encyclopedia
The alpha-1 adrenergic receptor is a G protein-coupled receptor
(GPCR) associated with the Gq
heterotrimeric G-protein. It consists of three highly homologous subtypes, including α1A-, α1B-, and α1D-adrenergic. Catecholamine
s like norepinephrine
(noradrenaline) and epinephrine
(adrenaline) signal through the α1-adrenergic receptor in the central
and peripheral nervous system
s.
, but also has specific effects of its own.
, which mainly constrict. However, there are other functions as well.
-Other substances: Efrain vinyl,Metharamanol,Mevin Terman.
s the principal effect is vasoconstriction
. Blood vessels with α1-adrenergic receptors are present in the skin
, the sphincters of gastrointestinal system, kidney
(renal artery
) and brain
. During the fight-or-flight response
vasoconstriction results in the decreased blood flow to these organs. This accounts for the pale appearance of the skin of an individual when frightened.
It also induces contraction of the urinary bladder
, although this effect is minor compared to the relaxing effect of β2-adrenergic receptor
s. In other words, the overall effect of sympathetic stimuli on the bladder is relaxation, in order to delay micturition during stress. Other effects are on smooth muscle are contraction in:
In a few areas the result on smooth muscle is relaxation. These include:
and partially mediates the efficacy of appetite suppressants
like phenylpropanolamine
and amphetamine
in the treatment of obesity
. Norepinephrine has been shown to decrease cellular excitability
in all layers of the temporal cortex, including the primary auditory cortex
. In particular, norepinephrine decreases glutamatergic
excitatory postsynaptic potential
s by the activation of α1-adrenergic receptors.
superfamily. Upon activation, a heterotrimeric G protein
, Gq
, activates phospholipase C
(PLC), which causes an increase in IP3 and calcium
. This triggers further effects, primarily through the activation of an enzyme Protein Kinase C. This enzyme, as a kinase, functions by phosphorylation of other enzymes causing their activation, or by phosphorylation of certain channels leading to the increase or decrease of electrolyte transfer in or out of the cell.
Antagonists
G protein-coupled receptor
G protein-coupled receptors , also known as seven-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors , comprise a large protein family of transmembrane receptors that sense molecules outside the cell and activate inside signal...
(GPCR) associated with the Gq
Gq alpha subunit
Gq protein or Gq/11 is a heterotrimeric G protein subunit that activates phospholipase C . PLC in turn hydrolyzes Phosphatidylinositol 4,5-bisphosphate to diacyl glycerol and inositol triphosphate signal transduction pathway...
heterotrimeric G-protein. It consists of three highly homologous subtypes, including α1A-, α1B-, and α1D-adrenergic. Catecholamine
Catecholamine
Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...
s like norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
(noradrenaline) and epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
(adrenaline) signal through the α1-adrenergic receptor in the central
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
and peripheral nervous system
Peripheral nervous system
The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...
s.
Effects
The α1-adrenergic receptor has several general functions in common with the α2-adrenergic receptorAlpha-2 adrenergic receptor
The alpha-2 adrenergic receptor is a G protein-coupled receptor associated with the Gi heterotrimeric G-protein. It consists of three highly homologous subtypes, including α2A-, α2B-, and α2C-adrenergic. Some species other than humans express a fourth α2D-adrenergic receptor as well...
, but also has specific effects of its own.
General
Common (or still unspecified) effects include:- VasoconstrictionVasoconstrictionVasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
of arteries to heartHeartThe heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
(coronary arteries) - Venoconstriction of veins
- Decrease motility of smooth muscleSmooth muscleSmooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
in gastrointestinal tractGastrointestinal tractThe human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
Specific
The primary effect is on smooth muscleSmooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
, which mainly constrict. However, there are other functions as well.
stimulators
-Noradrenaline,Adrenaline-Other substances: Efrain vinyl,Metharamanol,Mevin Terman.
Smooth muscle
In smooth muscle of blood vesselBlood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s the principal effect is vasoconstriction
Vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
. Blood vessels with α1-adrenergic receptors are present in the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, the sphincters of gastrointestinal system, kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
(renal artery
Renal artery
The renal arteries normally arise off the side of the abdominal aorta, immediately below the superior mesenteric artery, and supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle with the aorta....
) and brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
. During the fight-or-flight response
Fight-or-flight response
The fight-or-flight response was first described by Walter Bradford Cannon....
vasoconstriction results in the decreased blood flow to these organs. This accounts for the pale appearance of the skin of an individual when frightened.
It also induces contraction of the urinary bladder
Urinary bladder
The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
, although this effect is minor compared to the relaxing effect of β2-adrenergic receptor
Beta-2 adrenergic receptor
The beta-2 adrenergic receptor , also known as ADRB2, is a beta-adrenergic receptor, and also denotes the human gene encoding it.-Gene:The gene is intronless...
s. In other words, the overall effect of sympathetic stimuli on the bladder is relaxation, in order to delay micturition during stress. Other effects are on smooth muscle are contraction in:
- UreterUreterIn human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....
- HairHairHair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
s (arrector pili muscles) - UterusUterusThe uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
(when pregnant) - Urethral sphincterUrethral sphincterThe term urethral sphincter refers to one of two muscles used to control the exit of urine in the urinary bladder through the urethra. The two muscles are the external urethral sphincter and the internal urethral sphincter...
- Bronchioles (although minor to the relaxing effect of β2 receptor on bronchioles)
- Iris dilator muscleIris dilator muscleThe iris dilator muscle , is a smooth muscle of the eye, running radially in the iris and therefore fit as a dilator. It has its origin from the anterior epithelium. It is innervated by the sympathetic system, which acts by releasing noradrenaline, which acts on α1-receptors...
- Seminal tractSeminal tractThe seminal tract is a part of the male reproductive system and consists of Seminiferous tubules , Epididymis , Vas deferens and Ejaculatory duct....
, resulting in ejaculationEjaculationEjaculation is the ejecting of semen from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases ejaculation occurs because of prostatic disease...
In a few areas the result on smooth muscle is relaxation. These include:
- The rest of the GI tractGastrointestinal tractThe human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
, except for the sphincters - Blood vessels of erectile tissueErectile tissueErectile tissue is tissue in the body that can become erect, usually by becoming engorged with blood.-Erectile tissue in the clitoris and penis:...
Neuronal
Activation of α1-adrenergic receptors produces anorexiaAnorexia (symptom)
Anorexia is the decreased sensation of appetite...
and partially mediates the efficacy of appetite suppressants
Anorectic
An anorectic or anorexic , also known as anorexigenic or appetite suppressant, is a dietary supplement and/or drug which reduces appetite, food consumption, and as a result, causes weight loss to occur.-List of anorectics:Numerous pharmaceutical compounds are marketed as appetite suppressants.The...
like phenylpropanolamine
Phenylpropanolamine
Phenylpropanolamine , also known as the stereoisomers norephedrine and norpseudoephedrine, is a psychoactive drug of the phenethylamine and amphetamine chemical classes which is used as a stimulant, decongestant, and anorectic agent. It is commonly used in prescription and over-the-counter cough...
and amphetamine
Amphetamine
Amphetamine or amfetamine is a psychostimulant drug of the phenethylamine class which produces increased wakefulness and focus in association with decreased fatigue and appetite.Brand names of medications that contain, or metabolize into, amphetamine include Adderall, Dexedrine, Dextrostat,...
in the treatment of obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
. Norepinephrine has been shown to decrease cellular excitability
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...
in all layers of the temporal cortex, including the primary auditory cortex
Primary auditory cortex
The primary auditory cortex is the region of the brain that is responsible for the processing of auditory information. Corresponding roughly with Brodmann areas 41 and 42, it is located on the temporal lobe, and performs the basics of hearing—pitch and volume...
. In particular, norepinephrine decreases glutamatergic
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
excitatory postsynaptic potential
Postsynaptic potential
Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. Postsynaptic potentials are graded potentials, and should not be confused with action potentials although their function is to initiate or inhibit action potentials...
s by the activation of α1-adrenergic receptors.
Other
- Positive inotropic effect on heart muscle (α1<<β1) (in other words, strengthening the force of contraction)
- Secretion from salivary glandSalivary glandThe salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
- Increase salivary potassiumPotassiumPotassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
levels - GlycogenolysisGlycogenolysisGlycogenolysis is the conversion of glycogen polymers to glucose monomers. Glycogen is catabolized by removal of a glucose monomer through cleavage with inorganic phosphate to produce glucose-1-phosphate...
and gluconeogenesisGluconeogenesisGluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
from adipose tissueAdipose tissueIn histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
and liverLiverThe liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
. - Secretion from sweat glandSweat glandSweat glands, or sudoriferous glands, are small tubular structures of the skin that produce sweat. There are two kinds of sweat glands:...
s - Na+SodiumSodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
reabsorption from kidneyKidneyThe kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
- Stimulate proximal tubuleProximal tubuleThe proximal tubule is the portion of the duct system of the nephron of the kidney which leads from Bowman's capsule to the loop of Henle.-Structure and appearance:...
NHE3 - Stimulate proximal tubuleProximal tubuleThe proximal tubule is the portion of the duct system of the nephron of the kidney which leads from Bowman's capsule to the loop of Henle.-Structure and appearance:...
basolateral Na-K ATPase
- Stimulate proximal tubule
- Activate mitogenic responses and regulate growth and proliferation of many cells
- Involved in the detection of mechanical feedback on the hypoglossalHypoglossal nucleusThe hypoglossal nucleus is a cranial nerve nucleus, and it extends the length of the medulla, and being a motor nucleus, is close to the midline...
motor neurons which allow a long-term facilitation in respiration in response to repeated apneasApneaApnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
.
Signaling cascade
α1-Adrenergic receptors are members of the G protein-coupled receptorG protein-coupled receptor
G protein-coupled receptors , also known as seven-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors , comprise a large protein family of transmembrane receptors that sense molecules outside the cell and activate inside signal...
superfamily. Upon activation, a heterotrimeric G protein
Heterotrimeric G protein
"G protein" usually refers to the membrane-associated heterotrimeric G proteins, sometimes referred to as the "large" G proteins. These proteins are activated by G protein-coupled receptors and are made up of alpha , beta and gamma subunits, the latter two referred to as the beta-gamma...
, Gq
Gq alpha subunit
Gq protein or Gq/11 is a heterotrimeric G protein subunit that activates phospholipase C . PLC in turn hydrolyzes Phosphatidylinositol 4,5-bisphosphate to diacyl glycerol and inositol triphosphate signal transduction pathway...
, activates phospholipase C
Phospholipase C
Phosphoinositide phospholipase C is a family of eukaryotic intracellular enzymes that play an important role in signal transduction processes. In general, this enzyme is denoted as Phospholipase C, although three other families of phospholipase C enzymes have been identified in bacteria and in...
(PLC), which causes an increase in IP3 and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
. This triggers further effects, primarily through the activation of an enzyme Protein Kinase C. This enzyme, as a kinase, functions by phosphorylation of other enzymes causing their activation, or by phosphorylation of certain channels leading to the increase or decrease of electrolyte transfer in or out of the cell.
Activity during exercise
During exercise these α1-adrenergic receptors can be selectively blocked by sympathetic nervous activity, allowing the β2-adrenergic receptors (which mediate vasodilation) to dominate. Note that only the α1-adrenergic receptors in active muscle will be blocked. Resting muscle will not have its α1-adrenergic receptors blocked, and hence the overall effect will be α1-adrenergic-mediated vasoconstriction.Ligands
Agonists- CirazolineCirazolineCirazoline is a nonselective agonist of the alpha-1 adrenergic receptor , and an antagonist to the alpha-2 adrenergic receptor. It is believed that this combination of properties could make cirazoline an effective vasoconstricting agent....
- EtilefrineEtilefrineEtilefrine is a cardiac stimulant used as an antihypotensive. It is a sympathomimetic amine of the 3-hydroxy-phenylethanolamine series used in treating orthostatic hypotension of neurological, cardiovascular, endocrine or metabolic origin...
- MetaraminolMetaraminolMetaraminol is a potent sympathomimetic amine used in the prevention and treatment of hypotension, particularly as a complication of anesthesia.It is an α1-adrenergic receptor agonist with some β effect....
- MethoxamineMethoxamineMethoxamine is an α1-adrenergic receptor agonist, similar in structure to phenylephrine and 2,5-DMA. It was Developed by Burroughs-Wellcome in the 1940s. The drug induces vasoconstriction of skin and splanchnic blood vessels, thereby increasing peripheral vascular resistance and raising mean...
- MidodrineMidodrineMidodrine is a vasopressor/antihypotensive agent. Midodrine was approved in the United States by the Food and Drug Administration in 1996 for the treatment of orthostatic hypotension...
- ModafinilModafinilModafinil is an analeptic drug manufactured by Cephalon, and is approved by the U.S. Food and Drug Administration for the treatment of narcolepsy, shift work sleep disorder, and excessive daytime sleepiness associated with obstructive sleep apnea...
- NaphazolineNaphazolineNaphazoline is the common name for 2--2-imidazoline hydrochloride. It is a sympathomimetic agent with marked alpha adrenergic activity. It is a vasoconstrictor with a rapid action in reducing swelling when applied to mucous membrane...
- OxymetazolineOxymetazolineOxymetazoline is a selective alpha-1 agonist and partial alpha-2 agonist topical decongestant, used in the form of Oxymetazoline hydrochloride, in products such as Afrin, Dristan, Nasivin, Logicin, Vicks Sinex, Visine L.R., Sudafed OM, and Zicam. It was developed from Xylometazoline at E.Merck...
- PhenylephrinePhenylephrinePhenylephrine is a selective α1-adrenergic receptor agonist used primarily as a decongestant, as an agent to dilate the pupil, and to increase blood pressure...
(decongestantDecongestantA decongestant or nasal decongestant is a type of drug that is used to relieve nasal congestion.-Pharmacology:The vast majority of decongestants act via enhancing norepinephrine and epinephrine or adrenergic activity by stimulating the α-adrenergic receptors...
) - SynephrineSynephrineSynephrine is a drug commonly used for weight loss. While its effectiveness is widely debated, synephrine has gained significant popularity as an alternative to ephedrine, a related substance which has been made illegal or restricted in many countries due to health risks and its use as a precursor...
- TetrahydrozolineTetrahydrozolineTetrahydrozoline, a derivative of imidazoline, is found in over-the-counter eye drops and nasal sprays. Other derivatives include naphazoline, oxymetazoline, and xylometazoline. Poisoning can result from an overdose....
- XylometazolineXylometazolineXylometazoline is a drug which is used as a topical nasal decongestant. It is applied directly into the nose, either as a spray or as drops....
Antagonists
- AlfuzosinAlfuzosinAlfuzosin is an α1 receptor antagonist used to treat benign prostatic hyperplasia . It works by relaxing the muscles in the prostate and bladder neck, making it easier to urinate....
(used in benign prostatic hyperplasiaBenign prostatic hyperplasiaBenign prostatic hyperplasia also known as benign prostatic hypertrophy , benign enlargement of the prostate , and adenofibromyomatous hyperplasia, refers to the increase in size of the prostate.... - ArotinololArotinololArotinolol is a medication in the class of mixed alpha/beta blockers. -Uses:It is used in the treatment of high blood pressure.It has been proposed for use in treatment of essential tremor....
- CarvedilolCarvedilolCarvedilol is a non-selective beta blocker/alpha-1 blocker indicated in the treatment of mild to moderate congestive heart failure . It is marketed under various trade names including Carvil , Coreg , Dilatrend , Eucardic , and Carloc as a generic drug ., and as a...
(used in congestive heart failureCongestive heart failureHeart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
; it is a non-selective beta blocker) - DoxazosinDoxazosinDoxazosin mesylate, a quinazoline compound sold by Pfizer under the brand names Cardura and Carduran, is an α1a-selective alpha blocker used to treat high blood pressure and urinary retention associated with benign prostatic hyperplasia ....
(used in hypertensionHypertensionHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
and benign prostatic hyperplasia) - IndoraminIndoraminIndoramin is a piperidine antiadrenergic agent.It is an alpha-1 selective adrenoceptor antagonist. with direct myocardial depression action,therefore,it results in no reflex tachycardiaIt is commonly synthesized from tryptophol...
- LabetalolLabetalolLabetalol is a mixed alpha/beta adrenergic antagonist, which is used to treat high blood pressure.-Indications:...
(used in hypertensionHypertensionHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
; it is a mixed alpha/beta adrenergic antagonist) - MoxisylyteMoxisylyteMoxisylyte, also known as thymoxamine, is a drug used in urology used for the treatment of erectile dysfunction. It is an α1-adrenergic antagonist.- References :...
- PhenoxybenzaminePhenoxybenzaminePhenoxybenzamine is a non-selective, irreversible alpha antagonist.-Uses:It is used in the treatment of hypertension, and specifically that caused by pheochromocytoma...
- PhentolaminePhentolaminePhentolamine is a reversible nonselective alpha-adrenergic antagonist. -Mechanism:Its primary action is vasodilation due to α1 blockade....
(used in hypertensive emergencies; it is a nonselective alpha-antagonist) - PrazosinPrazosinPrazosin, trade names Minipress, Vasoflex, Pressin and Hypovase, is a sympatholytic drug used to treat high blood pressure and Anxiety, PTSD and Panic Disorder. It belongs to the class of alpha-adrenergic blockers. Specifically, prazosin is selective for the alpha-1 receptors on vascular smooth...
(used in hypertension) - SilodosinSilodosinSilodosin is a medication for the symptomatic treatment of benign prostatic hyperplasia...
- TamsulosinTamsulosinTamsulosin is an α1a-selective alpha blocker used in the symptomatic treatment of benign prostatic hyperplasia . Tamsulosin was developed by Yamanouchi Pharmaceuticals and is marketed by various companies under licence, including Boehringer-Ingelheim and CSL...
(used in benign prostatic hyperplasia) - TerazosinTerazosinTerazosin is a selective alpha 1 antagonist used for treatment of symptoms of an enlarged prostate...
- TolazolineTolazolineTolazoline is a non-selective competitive α-adrenergic receptor antagonist. It is a vasodilator that is used to treat spasms of peripheral blood vessels...
- TrimazosinTrimazosinTrimazosin is a sympatholytic drug.It is an alpha blocker.Hess, H. J.; 1972, .-References:...
Various heterocyclic antidepressant
Antidepressant
An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...
s and antipsychotic
Antipsychotic
An antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
s are α1-adrenergic receptor antagonists as well. This action is generally undesirable in such agents and mediates side effect
Side effect
In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequences of the use of a drug.Occasionally, drugs are...
s like orthostatic hypotension
Orthostatic hypotension
Orthostatic hypotension, also known as postural hypotension, orthostasis, and colloquially as head rush or dizzy spell, is a form of hypotension in which a person's blood pressure suddenly falls when the person stands up or stretches. The decrease is typically greater than 20/10 mm Hg, and may be...
.