Antihypertensive effects of propranolol are due to

• (1) Decreased myocardial contractility and rate

• (2) Consequences of decreased renin secretion.

Both effects occur as a consequence of beta-adrenoceptor blockade.

Decreased renin levels lead to decreases in circulating angiotensin II and effects on aldosterone levels.

Metoprolol is an example of a cardio-selective beta blocker, antagonizing mainly beta-1 receptors.

Cardioselective agents also, however, have effects at beta-2 sites and may be relatively contraindicated in certain clinical conditions, such as asthma or chronic obstructive pulmonary disease (COPD).

Beta receptor blockade causes:

• Decreases in myocardial contractility

• Increases in serum triglycerides and decreases in HDL cholesterol levels

• Increases in bronchial smooth muscle tone