Physiology and pharmacology of cardiovascular catecholamine receptors: implications for treatment of chronic heart failure.

In the sympathetic nervous system the physiologic effects of the endogenous catecholamines noradrenaline (NA) and adrenaline (A) are mediated by alpha- and beta-adrenoreceptors (ARs). Both AR-types can be subdivided into two major subtypes: alpha-ARs into alpha-1 (predominant effect: vasoconstriction) and alpha-2 (presynaptic: inhibition of NA-release; postsynaptic: vasoconstriction), beta-ARs into beta-1 (cardiac effects, renal renin release, and lipolysis) and beta-2 (presynaptic: facilitation of NA-release; postsynaptic: vascular, bronchial, and uterine smooth muscle relaxation, glycogenolysis and possibly part of the A-mediated cardiac effects). During the last 30 years growing evidence has accumulated that dopamine (DA), the third endogenous catecholamine and the immediate precursor of NA, may also cause peripheral effects through stimulation of specific DA-receptors, in addition to its known action at alpha- and beta-ARs. It is now well accepted that at least two different DA-receptors are present in many peripheral tissues (DA1 and DA2), including those of the cardiovascular and autonomic nervous system. They seem to be involved in dilation of certain vascular beds, inhibition of NA-release during nerve stimulation, natriuresis, and aldosterone release. In chronic heart failure cardiac beta-AR function decreases (presumably due to endogenous "down-regulation" by the elevated catecholamines), and this decrease is related to the severity of heart failure (judged clinically by New York Heart Association functional class). The human heart contains both functional beta-1 and beta-2 ARs; cardiac beta-1 and beta-2 ARs seem to be differentially affected by different kinds of heart failure; in end-stage dilated cardiomyopathy beta-1 ARs are selectively reduced, whereas beta-2 ARs are nearly normal.(ABSTRACT TRUNCATED AT 250 WORDS)