Adrenergic agonists Flashcards
What G-protein is alpha-1 receptor coupled to, and what signaling pathway does it activate?
The alpha-1 receptor is coupled to a Gq protein, which activates the IP3-DAG cascade, increasing intracellular calcium in smooth muscle cells.
What is the overall effect of alpha-1 receptor activation on peripheral arterial resistance?
Alpha-1 receptor activation increases peripheral arterial resistance by causing vasoconstriction in small arteries, and arterioles.
How does alpha-1 receptor activation influence venous return?
Alpha-1 receptor activation increases venous return by causing venoconstriction.
What effect does alpha-1 receptor activation have on mean arterial pressure?
Alpha-1 receptor activation increases mean arterial pressure through vasoconstriction.
alpha-1 receptor activation will occur where in the capillary bed?
precapillary sphincters.
How does alpha-1 receptor activation increase mean arterial pressure?
Alpha-1 receptor activation increases MAP by causing vasoconstriction in arteries and arterioles.
What effect does alpha-1 receptor activation have on the pupillary dilator muscle?
Alpha-1 receptor activation at the pupillary dilator muscle causes mydriasis, or pupillary dilation.
How does alpha-1 receptor activation affect the urethral sphincter and prostatic smooth muscle?
Alpha-1 receptor activation causes contraction of the urethral sphincter and prostatic smooth muscle.
What is the effect of alpha-1 receptor activation on urinary retention?
Alpha-1 receptor activation leads to urinary retention due to smooth muscle contraction.
What G-protein is alpha-2 receptor coupled to, and how does it affect cyclic AMP?
The alpha-2 receptor is coupled to a Gi protein, which decreases cyclic AMP levels.
What is the mechanism by which alpha-2 receptor activation reduces sympathetic tone?
Alpha-2 receptor activation reduces sympathetic tone by decreasing cyclic AMP levels in presynaptic neurons.
What is the primary central effect of alpha-2 agonists?
Alpha-2 agonists act centrally to reduce sympathetic tone, functioning as sympatholytics.
How does alpha-2 receptor activation at presynaptic terminals affect neurotransmitter release?
Alpha-2 receptor activation inhibits neurotransmitter release at presynaptic terminals.
What effect does alpha-2 activation have on insulin release from pancreatic islet cells?
Alpha-2 receptor activation decreases insulin release from pancreatic islet cells.
How does alpha-2 receptor activation affect lipolysis?
Alpha-2 receptor activation inhibits lipolysis and the release of free fatty acids.
What is the role of alpha-2 receptor activation in the ciliary body?
Alpha-2 receptor activation at the ciliary body reduces aqueous humor production.
What is a clinical use of brimonidine, an alpha-2 agonist?
Brimonidine, an alpha-2 agonist, is used to treat chronic open-angle glaucoma by decreasing aqueous humor production.
What G-protein is beta-1 receptor coupled to, and how does it affect cyclic AMP?
The beta-1 receptor is coupled to a Gs protein, which increases cyclic AMP levels.
What is the effect of beta-1 receptor activation on cardiac myocytes?
Beta-1 receptor activation increases cardiac contractility by increasing intracellular calcium in cardiac myocytes. Activation results in increased cardiac output.
What is the effect of beta-1 receptor activation on cardiac contractility and renin release?
Beta-1 receptor activation increases cardiac contractility and renin release, enhancing cardiac output and blood volume regulation.
How does beta-1 receptor activation influence heart rate?
Beta-1 receptor activation increases heart rate by enhancing activity at the sinoatrial node.
What is the effect of beta-1 receptor activation on renin release?
Beta-1 receptor activation increases renin release from juxtaglomerular apparatus cells.
What G-protein is beta-2 receptor coupled to, and what signaling pathway does it activate?
The beta-2 receptor is coupled to a Gs protein, which increases cyclic AMP and activates protein kinase A.
How does beta-2 receptor activation affect bronchial smooth muscle?
Beta-2 receptor activation causes bronchodilation by relaxing bronchial smooth muscle.
What is the effect of beta-2 activation in the lungs?
relaxes the muscles in the airways, which makes it easier to breathe (albuterol).
What effect does beta-2 receptor activation have on systemic vascular resistance?
Beta-2 receptor activation decreases systemic vascular resistance by causing vasodilation in coronary and skeletal muscle vasculature.
How does beta-2 receptor activation decrease systemic vascular resistance?
Beta-2 receptor activation decreases SVR by causing vasodilation in coronary and skeletal muscle vasculature.
How does beta-2 receptor activation influence lipolysis and glucose metabolism?
Beta-2 receptor activation stimulates lipolysis and gluconeogenesis, increasing free fatty acids and glucose levels.
What effect does beta-2 receptor activation have on insulin release from pancreatic islet cells?
Beta-2 receptor activation stimulates insulin release from pancreatic islet cells, promoting glucose uptake into cells.
What is the effect of beta-2 receptor activation on potassium levels?
Beta-2 receptor activation can cause hypokalemia by increasing insulin-mediated potassium uptake into cells.
How does beta-2 receptor activation influence aqueous humor production?
Beta-2 receptor activation increases aqueous humor production at the ciliary body.
What is the role of beta-2 agonists like albuterol in respiratory conditions?
Beta-2 agonists like albuterol are used in asthma and COPD to promote bronchodilation.
What are the effects of phenylephrine on MAP, systolic pressure, diastolic pressure, and heart rate?
Phenylephrine increases MAP, systolic pressure, and diastolic pressure through alpha-1 vasoconstriction and causes reflex bradycardia. This causes a decrease in cardiac output.
What is the role of phenylephrine in nasal congestion and pupillary dilation?
Phenylephrine is used in nasal congestion due to vasoconstriction and in pupillary dilation by acting on alpha-1 receptors.
What is the effect of the renal blood flow with the treatment of phenylephrine?
Decreases.
What is the mechanism of action and clinical use of norepinephrine in shock states?
Norepinephrine acts primarily on alpha-1 receptors to increase SVR and MAP, with beta-1 effects increasing cardiac contractility.
What type of shock is norepinephrine most commonly used in?
It is used in septic shock.
Why is norepinephrine the first-line agent in septic shock?
Norepinephrine is the first-line agent in septic shock because it increases systemic vascular resistance and venous return.
Does norepinephrine have a dose dependent dose effect?
No. The activity on alpha-1 receptors tends to be equal with Beta-1 receptors and these two receptors are activated significantly more than Beta-2 receptor activity.
Does norepinephrine alter the renal blood flow?
Yes, there is a decrease due to constriction of blood vessels, similar to phenylephrine.
Does norepinephrine have an affect on cardiac output?
No. The activity on alpha-1 receptors tends to be equal with Beta-1 receptors but the increase in systolic pressure that results from alpha-1 agonism, is balanced with the increase in myocardial contractilty due to the eqaual affect that NE has on both alpha-1 and Beta-1 (both are significantly more affected than Beta-2).
How does isoproterenol differ from norepinephrine in treating bradycardia and hypotension?
Isoproterenol primarily increases heart rate and reduces SVR, while norepinephrine increases SVR and modestly improves cardiac contractility.
What is the primary effect of dobutamine, and how is it used in cardiogenic shock?
Dobutamine is primarily used in cardiogenic shock.
vvvvvvvvvv
Dobutamine primarily acts on beta-1 receptors to increase cardiac output, heart rate, and contractility by increasing cAMP. The positive inotropic effect is due to the increased cAMP, causing an increased release of more calcium, improving contractility from the binding of calcium to tropomyosin (resulting in more actin-myosin interaction). The positive chronotropic effect (increased heart rate) is due to the increased intracellular cAMP concentration in pacemaker cells, speeding up the rate of heart contraction.
What occurs to the preload when giving dobutamine?
The increase in heart rate stimulated by dobutamine leads to shorter diastolic filling time and decreased left ventricular end diastolic volume, decreasing the preload.
Does dobutamine have any impact on Beta-2 receptors, what is the overall effect?
Dobutamine has a far more significant effect on Beta-1 receptors than Beta-2 receptors. Dobutamine, via its actions on beta-2 receptors, causes a small decrease in systemic vascular resistance and cardiac afterload.
Does dobutamine have any impact on alpha-1 receptors?
To a negligible degree.
Does dobutamine change renal blood flow?
Dobutamine has no effect on renal blood flow.
What occurs to the oxygen demand within cardiomyocytes with dobutamine?
Dobutamine increases (rather than decreases) myocardial oxygen demand by increasing contractility and heart rate. However, the effects of increasing oxygen demand are usually outweighted by the improvement in myocardial performance, particularly in patients without known ischemic heart disease.
Does dobutamine impact renal blood flow?
No.
How does isoproterenol influence systemic vascular resistance, heart rate, and pulse pressure?
Isoproterenol decreases systemic vascular resistance through beta-2 activation, increases heart rate via beta-1 activation, and increases pulse pressure and cardiac output.
What are the dose-dependent effects of epinephrine on systemic vascular resistance and cardiac output?
Epinephrine at low doses decreases SVR via beta-2 activation, while at high doses, it increases SVR via alpha-1 activation.
What happens to cardiac output when a patient is given EPI at low dose?
Increases (B1 > B2 > a1)
What happens to cardiac output when a patient is given EPI at high dose dose?
decreases (a1 > B1 > B2)
What happens to renal blood flow when a patient is given EPI at high dose dose?
decreases
How does epinephrine treat anaphylactic shock?
Epinephrine treats anaphylactic shock by increasing SVR via alpha-1 activation and causing bronchodilation via beta-2 activation.
What is the role of terbutaline and ritodrine in obstetrics?
Terbutaline and ritodrine relax uterine smooth muscle via beta-2 activation, preventing preterm labor.
