Question

How do A1 antagonists lower blood pressure?

A. By affecting both cardiac output and glomerular filtration rate
B. By increasing peripheral vascular resistance
C. By blocking postsynaptic receptors
D. By increasing the preload and afterload of the heart

Answer 1

A1 antagonists lower blood pressure by blocking postsynaptic receptors, leading to the relaxation of smooth muscles and dilation of blood vessels.

Step-by-step explanation:

A1 antagonists lower blood pressure by blocking postsynaptic receptors.

These antagonists specifically block the action of the alpha-1 adrenergic receptors, which are found in smooth muscle cells of blood vessels.

When these receptors are blocked, it prevents the binding of adrenaline (epinephrine) and noradrenaline (norepinephrine) to these receptors, resulting in relaxation of the smooth muscles and dilation of blood vessels. This dilation reduces peripheral vascular resistance, allowing blood to flow more easily, and therefore lowers blood pressure.