All of the following act by increasing nitric oxide except (AIIMS Nov 2012)
a. Sodium Nitroprusside - It is metabolized by blood vessels to its active metabolite, nitric oxide. It activates guanyl cyclase, which increase cGMP and cause vasodilatation.
b. Hydralazine - Much of action on vascular smooth muscle is not clearly known. It is partly endothelium dependent, may involve generation of nitric oxide and increasing cGMP.
c. Fenoldopam: α1 blocker against which lowers BP in severe hypertension on IV infusion dilates blood vessels of coronary, renal, mesenteric vessels.
d. Nitroglycerine: It forms nitric oxide which increase cGMP