Mechanism of Action

All of the p-blockers exert equilibrium-competitive antagonism of the actions of catecholamines and other adrenomimetics at p-receptors. Probably the best-recognized action of these compounds that is not mediated by a p-receptor is depression of cellular membrane excitability. This effect has been described as a membrane-stabilizing action, a quinidinelike effect, or a local anesthetic effect. This action is not too surprising in view of the structural similarities between p-blockers and local anesthetics. However, with the usual therapeu tic doses, the actions of the ß-receptor blocking agents appear to be almost entirely accounted for by their ß-re-ceptor antagonism.

Because the ß-receptors of the heart are primarily of the ß1 type and those in the pulmonary and vascular smooth muscle are ß2 receptors, ß1-selective antagonists are frequently referred to as cardioselective blockers. The intrinsic activity, cardioselectivity, and membrane-stabilizing actions of a number of ß-blockers are summarized in Table 11.2

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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