<prompt> The mechanism of action of sodium nitroprusside is?Increased cAMPIncreased guanylate cyclaseCalcium channel blockageIC channel opener  <response>: Ans. is b i.e., Increases Guanyl Cyclase o Nitroprusside dilates both aerial and venous vessels, resulting in reduced peripheral vascular resistance and venous return. The action occurs as a result of activation of guanylyl cyclase, either release of nitric oxide or by direct stimulation of enzyme. The result is increased intracellular cGMP, which relaxes vascular smooth muscle. 