All of the following statements about antianginal action of nitrates are true except?

Ans. is 'c' i.e., Total coronary flow Pharmacological actions of nitrates The only major action is direct nonspecific smooth muscle relaxation. The most prominant action is exeed on vascular smooth muscles. Preload reduction - Nitrates dilate veins more than aeries decreased venous return (preload) - decreased end diastolic size and pressure - decreased O2 consumption. Afterload reduction - Nitrates also produce some aeriolar dilatation - slightly decreased total peripheral resistance (afterload). Redistribution of coronary flow. Other smooth muscles - Nitrates cause relaxation of bronchi, biliary tract, esophagus - can be used in biliary colic and esophageal spasm.