Increased forskolin stimulation of lymphocyte-adenylate cyclase in normotensive subjects predisposed to essential hypertension

Since a significant heritabiiity has been shown for forskolin stimulation of lymphocyte adenylate cyclase activity in twins, we evaluated lymphocyte forskolin-stimulated adenylate cyc-lase activity with respect to a familial predisposition towards essential hypertension. Lymphocyte adenylate cyclase activity was measured in broken cell preparations of 32 male normotensive volunteers with (n = 15) and without (n = 17) a positive family history of hypertension. The maximal forskolin stimulation of adenylate cyclase activity was significantly higher in the positive com-pared with the negative group (maximal stimulation of ac- itvity 53.5 ± 3.4 versus 41.2 ± 1.9pmol cyclic AMP (cAMP)/mg protein per min; P< 0.01). Dose-response curves showed a significantly greater stimulation of adenylate cyclase activity in the positive group at forskolin concentrations of 10^-7to 2 x 10^-4mol/l. The median effective dose (ED₅₀) and adenylate cyclase activity in the absence of forskolin were similar in both groups. We conclude that lymphocyte forskolin-stimulated adenylate cyclase activity may depend in part on hereditary factors associated with a familial predisposition to essential hypertension.