The reader should refer to a drug handbook for details about dosage and side effects. ACE inhibitors prevent the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor. Less angiotensin II means decreased peripheral arterial resistance, resulting in decreased aldosterone secretion. These complex reactions cause reduced sodium and water retention, and thus lower blood pressure. The sympathetic nervous system controls many bodily functions through the neurotransmitter norepinephrine.
Alpha blockers act at alpha receptor sites to reduce peripheral vascular resistance.
They produce vasodilation, resulting in lower blood pressure. Beta blockers inhibit beta receptors, resulting in decreased cardiac output, decreased cardiac oxygen consumption, and reduced peripheral vascular resistance. Calcium channel blockers work to lower blood pressure in a different way. For muscular contraction to occur, calcium ions must move from the outside of cells to the inside. Calcium channel blockers inhibit the movement of calcium ions.