Alpha- and beta-adrenoceptors in circulating blood cells of essential hypertensive patients: increased receptor density and responsiveness.
In 40 male patients with established essential hypertension (P diast greater than 95 mmHg) platelet alpha 2-adrenoceptor density (by 3H-yohimbine binding) and -responsiveness (by adrenaline-induced aggregation) as well as lymphocyte beta 2-adrenoceptor density (by (+/-)-125 iodocyanopindolol binding) and -responsiveness (by cyclic AMP responses to isoprenaline) were determined and compared with those in 40 male age-matched normotensives (P diast less than 90 mmHg). In essential hypertensive patients mean platelet alpha 2- and lymphocyte beta 2-adrenoceptor densities were significantly increased. When data from all 80 subjects were combined, significant positive correlations between mean arterial blood pressure and alpha 2- and beta 2-adrenoceptor densities, respectively, were found. The increases in alpha 2- and beta 2-adrenoceptor densities were accompanied by enhanced responsiveness to adrenergic stimulation: in platelets adrenaline-induced aggregation--via alpha 2-adrenoceptor stimulation--was exaggerated, and in lymphocytes isoprenaline produced significantly greater increases in the intracellular level of cyclic AMP. It is concluded that the increased density and responsiveness of alpha 2-and beta 2-adrenoceptors in circulating blood cells of essential hypertensive patients may reflect increased sympathetic activity, which might contribute to the elevation of blood pressure.
D000262:Adenylyl Cyclases / Q000378:metabolism; D001773:Blood Cells / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism; D001794:Blood Pressure; D004789:Enzyme Activation; D006801:Humans; D006973:Hypertension / Q000097:blood*; D008214:Lymphocytes / Q000378:metabolism; D010974:Platelet Aggregation; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D000262:Adenylyl Cyclases