Which of the following statements is true about nitrates?

Ans. (D) All of the above(Ref: KDT 8th/e p586, 587, 590)Nitrates act by releasing NO which increases cGMP that cause dephosphorylation of myosin light chain kinase. These are preferential dilator of venules because glutathione reductase (enzyme that releases NO from nitrates) is principally present at these sites. These agents are smooth muscle relaxants and can be used in colics and in achlasia cardia.