Plasma catecholamines and adrenoceptors in young hypertensive patients.

An elevated sympathoadrenal tone and an imbalance in postsynaptic alpha- and beta-adrenoceptor function are discussed as factors in the pathogenesis of essential hypertension. This study examined plasma catecholamines, thrombocyte alpha2-adrenoceptors and lymphocyte beta2-adrenoceptors in 16 young patients with newly detected essential hypertension and 26 normotensive age matched controls (27.1 +/- 4.5 vs. 24.8 +/- 2.8 years; NS). Plasma noradrenaline (276 +/- 34 vs. 216 +/- 18 pg/ml, P < 0.05) and plasma adrenaline (96 +/- 15 vs. 31 +/- 4 pg/ml, P < 0.0001) were significantly elevated in hypertensive patients. Thrombocyte alpha2-adrenoceptor density was only nonsignificantly decreased (230 +/- 37 vs. 311 +/- 36 fmol/mg protein, NS), whereas lymphocyte beta2-adrenoceptor density was markedly reduced (15.3 +/- 2.3 vs. 22.6 +/- 1.8 fmol/mg protein, P < 0.01) in hypertensive patients. Elevated plasma catecholamines are consistent with a pathophysiological role for increased sympathetic neural activity in young hypertensive patients. Assuming that results of adrenoceptor studies on blood elements are applicable on vascular receptors, our results are consistent with an imbalance of postsynaptic adrenoceptor functions which promotes the pressor effects of the sympathetic system.