Ethnic differences in cyclic AMP accumulation: effect on alpha 2, beta 2, and prostanoid receptor responses.

Platelet alpha 2- and lymphocyte beta 2-adrenergic receptor density and responsiveness and platelet responses to prostaglandin E2 (PGE2) were measured in black subjects and white subjects. Mean (+/- SEM) alpha-receptor density was greater in white subjects (248 +/- 29 versus 392 +/- 31 fmol/mg protein; p less than 0.005), whereas beta-receptor densities were similar (black subjects, 19.2 +/- 2.2 fmol/mg protein; white subjects, 15.2 +/- 1.4 fmol/mg protein). Basal platelet cyclic AMP levels (black subjects, 7.8 +/- 1.1 pmol/mg protein; white subjects, 14.5 +/- 2.4 pmol/mg protein; p less than 0.05) and PGE2-induced increases in platelet cyclic AMP levels were higher in white subjects (black subjects, 47.1 +/- 3.3 pmol/mg protein; white subjects, 65.5 +/- 3.4 pmol/mg protein; p less than 0.001). Basal lymphocyte cyclic AMP levels (black subjects, 1.2 +/- 0.3 pmol/10(6) cells; white subjects, 2.8 +/- 0.6 pmol/10(6) cells; p less than 0.05) and mean isoproterenol-induced cyclic AMP increases were also higher in white subjects (black subjects, 6.2 +/- 0.6 pmol/10(6) cells; white subjects, 8.5 +/- 0.8 pmol/10(6) cells; p less than 0.05). Responses to isoproterenol as fold stimulation of basal were not significantly higher in black subjects (8.51 +/- 0.97 versus 6.16 +/- 0.86 fold-stimulation of basal). Platelet responses to PGE2 as fold stimulation of basal (black subjects, 7.9% +/- 0.7%; white subjects, 8% +/- 1.3%) and alpha 2-receptor-mediated inhibition of PGE2 responses by UK-14304 (black subjects, 38.2% +/- 1.7%; white subjects, 40.6% +/- 2.3%) were also similar in the two groups.