Which of the following is beta-blocker antagonist -

Ans. is 'a' i.e., ??? Glucagon (may be) o Glucagon is used in beta-blocker poisoning to combat bradycardia produced by b-blockers. Glucagon acts by increasing C-GMP in myocardium, in effect bypassing b-receptors - Action is independent of beta receptors.b-blocker poisoningo Overdose, including self poisoning, causes bradycardia, heart block, hypotension and low output heart failure that can proceed to cardiogenic shocko Death is more likely with agents having membrane stabilizing action.o Severe bronchoconstriction may occur.o Loss of conciousness may occur with lipid-soluble agents that penetrate the CNS.Treatment of b-blocker poisoning.o Atropine - is used to eliminate unopposed vagal activity that contribute to bradycardiao Glucagon and calcium - Are used for hypotension and symptomatic bradycardiao Isoprenaline can be used if there is no response. It has direct cardiac stimulant action via b1 receptorso Other sympathomimetics may be used according to desired agonist actions (b1, b2, a) required by the clinical conditions, e.g. dobutamine, dopamine, dopexaminey adrenaline, noradrenaline.o Amrinone can be used for inotropic effect.o Salbutamol or aminophylline may be used to counteract bronchoconstriction.