Plasma catecholamines, thrombocyte alpha 2- and lymphocyte beta 2-adrenoceptor densities in hypertensive patients with low or normal plasma renin concentrations.

The sympathetic nervous system is unique in the regulation of plasma renin, for it can stimulate or suppress renin release by activation of either renal beta- or alpha 2-adrenoceptors. The authors studied plasma renin concentration (PRC), noradrenalin and adrenalin levels in plasma, and the densities of lymphocyte beta 2-adrenoceptors and thrombocyte alpha 2-adrenoceptors in 25 hypertensive patients with either normal (11-40 mU/L; n = 9) or low PRC (0-10 mU/L; n = 14). There were no differences in plasma catecholamine levels and adrenoceptor densities between the two patient groups. A positive correlation (r = 0.66; P < 0.005) between beta 2-adrenoceptor density and PRC in the patient group with low PRC, and a negative correlation (r = -0.72; P < 0.01) between alpha 2-adrenoceptor density and plasma renin in patients with normal PRC were found. They conclude that adrenoceptor densities on blood elements and plasma catecholamines do not differ in low and normal renin hypertension. The significant correlations between adrenoceptor densities and PRCs may indicate that adrenoceptors on blood elements mirror adrenoceptor densities in the kidney and that tonic suppression of renin release through alpha 2-adrenoceptors is preserved in hypertensive patients with normal plasma renin levels.