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Questions and Answers
Activation of the α1 receptor in vascular smooth muscle leads to vasoconstriction through which of the following signaling pathways?
Activation of the α1 receptor in vascular smooth muscle leads to vasoconstriction through which of the following signaling pathways?
- Activation of phospholipase C, increasing DAG and IP3, leading to increased intracellular calcium and protein kinase C activation. (correct)
- Inhibition of adenylyl cyclase, decreasing cAMP, and reducing calcium influx.
- Activation of adenylyl cyclase, increasing cAMP, and activating protein kinase A.
- Direct activation of Rho kinase, leading to increased myosin light chain phosphatase activity.
Which of the following is the most likely effect of stimulating β2-adrenergic receptors in bronchial smooth muscle?
Which of the following is the most likely effect of stimulating β2-adrenergic receptors in bronchial smooth muscle?
- Bronchodilation mediated by increased cAMP and PKA activity. (correct)
- Bronchodilation due to decreased cAMP and increased MLCK activity.
- Bronchoconstriction mediated by activation of Rho kinase and inhibition of myosin light chain phosphatase.
- Bronchoconstriction due to increased intracellular calcium.
Activation of M3 receptors on endothelial cells leads to vasodilation via which of the following mechanisms?
Activation of M3 receptors on endothelial cells leads to vasodilation via which of the following mechanisms?
- Increased cAMP production, leading to activation of PKA and subsequent vasodilation
- Inhibition of adenylyl cyclase, reducing cAMP levels, and increasing calcium influx.
- Activation of phospholipase C, leading to increased DAG and IP3 production and stimulation of NO synthesis. (correct)
- Decreased cAMP production, leading to reduced PKA activity and calcium influx.
Which of the following best describes the downstream effect of alpha-2 (α2) receptor activation in the pre-synaptic nerve terminal?
Which of the following best describes the downstream effect of alpha-2 (α2) receptor activation in the pre-synaptic nerve terminal?
What is the primary mechanism by which activation of the β1 receptor in the heart affects cardiac function?
What is the primary mechanism by which activation of the β1 receptor in the heart affects cardiac function?
How does activation of the M2 receptor in the heart affect heart rate and contractility?
How does activation of the M2 receptor in the heart affect heart rate and contractility?
A drug that selectively activates α1-adrenergic receptors would be expected to have which of the following effects on blood pressure and peripheral resistance?
A drug that selectively activates α1-adrenergic receptors would be expected to have which of the following effects on blood pressure and peripheral resistance?
How does norepinephrine (NE) affect renin release in the kidney, and which receptor type mediates this effect?
How does norepinephrine (NE) affect renin release in the kidney, and which receptor type mediates this effect?
What is the role of Myosin Light Chain Kinase (MLCK) in smooth muscle contraction, and how is it affected by the α1 receptor activation?
What is the role of Myosin Light Chain Kinase (MLCK) in smooth muscle contraction, and how is it affected by the α1 receptor activation?
A patient with asthma is administered a non-selective beta-adrenergic agonist. Which of the following side effects is most likely to occur due to the drug's action on β1 receptors?
A patient with asthma is administered a non-selective beta-adrenergic agonist. Which of the following side effects is most likely to occur due to the drug's action on β1 receptors?
Flashcards
α1 Receptor
α1 Receptor
Activates PLC, converting PIP2 into DAG and IP3, leading to increased intracellular calcium and smooth muscle contraction, ultimately causing vasoconstriction.
α2 Receptor
α2 Receptor
Inhibits adenylyl cyclase, reducing cAMP levels and sympathetic outflow from presynaptic nerve terminals.
β1 Receptor
β1 Receptor
Activates adenylyl cyclase, increasing cAMP levels, leading to increased heart rate, contractility, and renin release from the kidneys.
β2 Receptor
β2 Receptor
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M2 Receptor
M2 Receptor
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M3 Receptor
M3 Receptor
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Study Notes
- The provided documents cover adrenergic and cholinergic receptors, their functions, and signaling pathways.
Adrenergic Receptors
- Adrenergic receptors bind norepinephrine (NE) and epinephrine (Epi).
- They are involved in various physiological effects like vasoconstriction, bronchodilation, and regulation of heart rate.
α1 Receptors
- Neurotransmitter: NE
- Tissue: VSM (Vascular Smooth Muscle), Visceral smooth muscle
- G-protein class: Gq
- Second messenger pathway: Activates PLC, converting PIP2 into DAG + IP3
- DAG stimulates PKC
- IP3 increases Ca release, leading to a Ca/Calmodulin complex stimulating MLCK. This then leads to Myosin-P+actin contraction.
- Also activates Rho kinase, which inhibits MLCP.
- Effects on VSM: Contraction and Vasoconstriction
- Other functions: Pupillary dilator muscle contraction (mydriasis and intestinal and bladder sphincter muscle contraction
α2 Receptors
- Neurotransmitter: NE
- Tissue: Presynaptic nerve terminal
- G-protein class: Gi
- Second messenger pathway: Inhibits adenylyl cyclase, decreasing the conversion of ATP to cAMP
- Decreased cAMP stimulation of PKA leads to decreased Ca.
- Effect: Decreases sympathetic (adrenergic) outflow.
- Other functions: insulin release, lipolysis, platelet aggregation, and aqueous humor production
β1 Receptors
- Neurotransmitter: NE/Epi
- Tissues: Heart and Kidney
- G-protein class: Gs
- Second messenger pathway: Activates adenylyl cyclase, increasing the conversion of ATP to cAMP.
- cAMP stimulates PKA, increasing Ca release.
- Effects: Increased heart rate, contractility, and renin release.
- Other functions: increased heart rate, contractility (one heart), renin release, lipolysis
β2 Receptors
- Neurotransmitter: Epi
- Tissues: VSM, Bronchial smooth muscle
- G-protein class: Gs
- Second messenger pathway: Activates adenylyl cyclase, increasing the conversion of ATP to cAMP.
- cAMP stimulates PKA, increasing Ca release.
- Effects: Vasodilation and Bronchodilation
- Other functions: vasodilation, bronchodilation (two lungs), lipolysis, insulin release, glycogenolysis, uterine tone (tocolysis), aqueous humor production, and cellular K uptake
β3 Receptors
- Effect: increased lipolysis, thermogenesis in skeletal muscle, and bladder relaxation
Cholinergic Receptors
- Cholinergic receptors bind acetylcholine (Ach).
- They are involved in functions like smooth muscle contraction, glandular secretions, and heart rate control.
M2 Receptors
- Neurotransmitter: Ach
- Tissue: Heart
- G-protein class: Gi
- Second messenger pathway: Inhibits adenylyl cyclase, decreasing the conversion of ATP to cAMP.
- cAMP stimulates PKA, which inhibits MLCK.
- Effects: Decreased heart rate, and contractility.
M3 Receptors
- Neurotransmitter: Ach
- Tissues: Bronchial smooth muscle, endothelial cells
- G-protein class: Gq
- Second messenger pathway: PLC converts PIP2 into DAG + IP3
- DAG stimulates PKC
- IP3 stimulates Ca release.
- Effects: Bronchoconstriction and Vasodilation
- Other functions: exocrine gland secretions (eg, lacrimal, sweat, salivary, gastric acid), gut peristalsis, bladder contraction, bronchoconstriction, pupillary sphincter muscle contraction (miosis), ciliary muscle contraction (accommodation), insulin release, and endothelium-mediated vasodilation
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