Medical Pharmacology
Sodium nitroprusside (Abbreviated SNP, brand name: Nitropress) has potent vasodilating effects in arterioles and venules (venules more than arterioles, but this selectivity is much less marked than that of nitroglycerin). It is administered intravenously in cases of acute hypertensive emergency. SNP breaks down in circulation to release nitric oxide (NO). NO activates guanylate cyclase in vascular smooth muscle and increases intracellular production of cGMP. cGMP activates Protein Kinase G which activates phosphatases which inactivate Myosin light chains. Myosin light chains are involved in muscle contraction. The end result is vascular smooth muscle relaxation, which allow vessels to dilate.
In the human heart, nitric oxide reduces both total peripheral resistance as well as venous return, thus decreasing both preload and afterload. For this reason, it can be used in severe cardiogenic heart failure where this combination of effects can act to increase cardiac output. In situations where cardiac output is normal, the effect is to reduce blood pressure.
Read more about this topic: Sodium Nitroprusside
Famous quotes containing the word medical:
“There may perhaps be a new generation of doctors horrified by lacerations, infections, women who have douched with kitchen cleanser. What an irony it would be if fanatics continued to kill and yet it was the apathy and silence of the medical profession that most wounded the ability to provide what is, after all, a medical procedure.”
—Anna Quindlen (b. 1952)