<prompt> Antihypeensives act by all of the following mechanism except: March 2012Na. ATPase inhibitionAlpha adrenergic blockadeBeta adrenergic blockadePotassium channel opener  <response>: Ans: A i.e. Na K ATPase Antihypeensives and mechanism of action Digitalis increases increase force of cardiac contraction cardiac inotropic by selectively binding to extracellular face of the membrane associated Na K ATPase of myocardial fibres and inhibits it. Digitalis is used in congestive hea failure and cardiac arrhythmias. Prazosin, terazosin, doxazosin, phentolamine and phenoxybenzamine are alpha adrenergic blocking anti-hypeensive drugs. Propranolol, metoprolol, atenolol etc. are some of the beta adrenergic blocking anti-hypeensive drugs Minoxidil and diazoxide are potassium channel openers which were used earlier in severe hypeension and hypeensive emergencies. 