what is the main mode of action of beta-blockers in controlling hypertension ?
a) decrease cardiac input
b) slow the heart rate
c) increase the cardiac force of contraction
d) increase cardiac output
e) decrease plasma volume
Answer:
b) slow the heart rate
Explanation
Beta-blockers act by blocking the action of noradrenaline at b adrenoceptors throughout the circulatory system and elsewhere. Their major effect is to slow the heart rate and reduce its force of contraction. beta-blockers also cause some reduction in renin release and central sympathetic tone.