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D.Pharm, B.Pharm, and Pharm.D. Exams
RRB Pharmacist Recruitment Exam
Common Recruitment Examination for AIIMS Pharmacist
KGMU Pharmacist Recruitment Exam
KSSSCI Pharmacist Recruitment Exam
MPESB Pharmacist Recruitment Exam
Drugs Inspector Exams
Drugs Controller Exams
DPEE
Adrenergic receptors (α and β receptors) are the receptors which mediate the actions of noradrenaline (norepinephrine) and adrenaline (epinephrine).
All of the adrenergic receptors are membrane bound G-protein coupled receptors.
Adrenergic receptors function primarily by increasing or decreasing the intracellular production of second messengers cAMP or IP3/DAG.
In some cases the activated G-protein itself operates K+ or Ca2+ channels, or increases prostaglandin production.
The adrenergic receptors are classified on the basis of their apparent drug sensitivity.
They are classified as α and β-receptors.
α-receptors are further subdivided as α1 and α2.
α1A, α1B, and α1D are subtypes of α1 receptors.
α2A, α2B, and α2C are subtypes of α2 receptors.
β-receptors are subdivided as β1, β 2, and β 3 receptors.
The rank order of agonist potency for α-receptors is epinephrine > norepinephrine >> isoproterenol.
The rank order of agonist potency for β -receptors is isoproterenol > epinephrine > norepinephrine.
The α1 receptor is a G-protein coupled receptor generally an excitatory receptor connected to the Gq G-protein.
The α1 receptors can be thought of as a receptor of contraction.
α1 receptors are found at: vascular smooth muscles, bronchial smooth muscle, radial smooth muscles of iris, pilomotor smooth muscles, prostate, urinary bladder and anal sphincter, mucous membrane, uterus and in the CNS neurons.
The α2 receptor is an inhibitory G-protien coupled receptor connected to the Gi G-protein.
Once activated by the α2 receptor, Gi inhibits adenylyl cyclase, and cause intracellular cAMP levels to decrease.
Within sympathetic nervous system, α2 receptors are found on the presynaptic terminals of postganglionic sympathetic neurons and inhibit further release of norepinephrine.
α2 receptors are the primary adrenergic receptor within the CNS.
α2 receptors are also found at pancreatic islets which cause inhibition of insulin release and at platelets cause platelet aggregation.
All of the β receptors are generally excitatory GPCR connected to the Gs G-protein.
Stimulation of β receptor activates Gs G-protein which then activates adenylyl cyclise and the generation of intracellular cAMP. This starts a chain of events that lead to the effects of β receptor activation.
β1 receptors are typically found at myocardium in the heart and juxtaglomerular cells in kidneys. They are also found in the CNS and adipose tissues.
The most important effects of stimulation of beta1 receptors are:
o Increased heart rate and contractility.
o Increased release of renin.
o In the CNS, it causes ADH secretion from posterior pituitary gland that enhances renal salt and water reabsorption.
o In adipocytes, it enhances lipolysis.
β2 receptors are typically found at bronchi, blood vessels, uterus, liver, G.I.T., urinary tract, eye. They are not predominant in the heart.
The physiological action of β2 receptors is mainly due to relaxation of smooth muscle and modulation of hepatic metabolism.
Their activation causes bronchodilation, vasodilation, low B.P., uterine relaxation, stimulation of glycogenolysis and gluconeogenesis, increased blood glucose concentration.
β3 receptors are typically found at adipose tissue and detrusor muscle of bladder.
Their activation increase lipolysis and urinary bladder relaxation.
MCQs
1. The receptors which mediate the action of epinephrine or norepinephrine are ____
a) Adrenergic receptors
b) Nephrogenic receptors
c) Cholinergic receptors
d) Angiotensin receptors
2. All of the adrenergic receptors are ______
a) G-protein coupled receptors
b) Ion channel receptors
c) Enzyme linked receptors
d) Nuclear receptors
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Blog content and MCQs have been taken from the following:
1) Essential Pharmacy Review for Drugs Inspector Exams by Nirali Prakashan, Pune
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2) Pharmacist Recruitment Exam by Nirali Prakashan, Pune
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To know more about our DPEE book DIPLOMA IN PHARMACY EXIT EXAMINATION (DPEE) – Based on PCI-ER 2020 Syllabus (5000+ MCQs)
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PHARMACOLOGY (Second Year Diploma in Pharmacy PCI – ER 2020)
Authors: Sunil R. Bakliwal , Praneta R. Desale , Pravin P. Jawale
This book includes more than 500 MCQs for the preparation of DPEE and various Pharmacist Recruitment Exams
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