Class IV antidysrhythmics or calcium channel blockers have what action on the cardiovascular system?

Alpha 1 adrenergic blocking agents have a vasodilating effect and can be used for the management of hypertension. They work by blocking the alpha 1 receptors on the vascular smooth muscle, which normally cause vasoconstriction when stimulated by catecholamines like epinephrine and norepinephrine.By preventing this constriction, alpha 1 blockers lower the peripheral resistance and blood pressure

Choice A is wrong because alpha 3 adrenergic blockers do not exist.There are only two types of alpha receptors: alpha 1 and alpha 2

Choice B is wrong because alpha 2 adrenergic antagonists do not have a vasodilating effect.

They block the alpha 2 receptors, which are located presynaptically on the sympathetic nerve terminals and postsynaptically on some vascular smooth muscle cells.Alpha 2 receptors inhibit the release of norepinephrine when activated, so blocking them would increase the sympathetic activity and vasoconstriction

Choice C is wrong because alpha 1 adrenergic agonists do not have a vasodilating effect.

They stimulate the alpha 1 receptors, which cause vasoconstriction and increase the blood pressure.Alpha 1 agonists are used to treat hypotension and nasal congestion

This is because potassium sparing diuretics do not lower potassium levels in the blood, unlike some other types of diuretics. Potassium is an important electrolyte that helps regulate nerve and muscle functions, especially the heart. Low potassium levels can cause irregular heartbeats and other problems.Therefore, people who take diuretics should avoid foods that are high in potassium, such as bananas, oranges, tomatoes, and potatoes, unless they are taking potassium sparing diuretics.

Choice A is wrong because thiazide diuretics, such as hydrochlorothiazide, can cause low potassium levels in the blood and increase the risk of arrhythmias.

People who take thiazide diuretics may need to take potassium supplements or eat more potassium-rich foods.

Choice B is wrong because osmotic diuretics, such as mannitol, do not affect potassium levels in the blood.

They work by increasing the amount of water in the urine, but do not alter the electrolyte balance.

Osmotic diuretics are mainly used to treat brain swelling or glaucoma.

Choice D is wrong because loop diuretics, such as lasix, can also cause low potassium levels in the blood and increase the risk of arrhythmias.

People who take loop diuretics may also need to take potassium supplements or eat more potassium-rich foods.

Normal ranges for potassium in the blood are 3.5 to 5.0 millimoles per liter (mmol/L).