α- and β-Adrenoceptors in Hypertension. II. Platelet α2- and Lymphocyte β2-Adrenoceptors in Children of Parents with Essential Hypertension. A Model for the Pathogenesis of the Genetically Determined Hypertension

SummaryTo study whether changes in α- and β-adrenoceptors in human essential hypertension (EHT) might be genetically determined, we assessed platelet α2- and lymphocyte β2-adrenoceptor density in 48 normotensive children of normotensive parents (NT) and in 41 normotensive children with one EHT-parent. Both groups did not differ in age, body weight and height, blood pressure, heart rate, plasma catecholamine levels, plasma renin activity (PRA), and lymphocyte β2-adrenoceptor density. Platelet α2-adrenoceptor density, however, was in EHT-children significantly higher than in NT-children. In NT-children, platelet α2-adrenoceptors were significantly, inversely correlated with PRA, indicating that they might mirror renal α2-adrenoeeptors which inhibitorily regulate renin release. In contrast, in EHT-children PRA was not at all related to platelet α2-adrenoceptors, suggesting an early (even in the normotensive stage) disturbance of the α2-adrenoceptor-mediated regulation in renin release. From these results and those obtained in the experimental rat models of acquired hypertension, a model for the pathogenesis of the genetically determined hypertension is proposed in which a very early step in the development of hypertension is a genetically determined increase in renal α-adrenoceptors that causes enhanced sodium retention. This initiates a chain of events that finally results in increased peripheral vascular resistance and, hence, blood pressure. On the other hand. β-adreno-ceptor changes seem to be secondary phenomena due to the elevation in blood pressure.