DrVirgo
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13. An experimental drug is administered to a human subject with moderately severe congestive heart failure. Within minutes of intravenous administration, there is a measurable decrease in cardiac preload and cardiac afterload, and an increase in glomerular filtration rate. The effects of the drug are most similar to those produced by which of the following?
A) ADH (vasopressin)
B) Aldosterone
C) Angiotensin II
D) Atrial natriuretic peptide
E) Insulin
F) Norepinephrine
D???
Can anyone explain the mechanism of action of ANP?
Thanks. 
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| robin082006
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Yes D, we can exclude other choices easily, NE and Angiotensin II cause vasocontriction, ALdosterone and Vasopressin act on renal tubules, insulin has no effects on preload and afterload.
About natriuretic peptide (copied):
- Dilates the afferent glomerular arteriole, constricts the efferent glomerular arteriole--> increase glomerular filtration rate - Decreases sodium resorption in the renal distal convoluted tubule and cortical collecting duct. - Inhibits renin secretion.
- Relaxes vascular smooth muscle in arterioles and venules by Receptor-mediated elevation of vascular smooth muscle cGMP and Inhibition of the effects of catecholamines
- Reduces aldosterone production by the adrenal rtex.
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| DrVirgo
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Yes.
ANP is released when there is volume overload of the heart... I think of ANP's actions simply as the opposite of ADH's actions... (ANP is like a diuretic, and it causes loss of volume, rather than gain of volume like ADH)...
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