title: Endogenous and exogenous regulation of human alpha- and beta-adrenergic receptors.
abstract: Regulation of human beta 2-adrenergic receptors in lymphocytes (determined by (+/-)-125iodocyanopindolol (ICYP) binding) and alpha 2-adrenergic receptors in platelets (determined by 3H-yohimbine binding) was studied. While beta 2-adrenergic receptor number did not change with age, a significant negative correlation between the number of alpha 2-adrenergic receptors and age was found; plasma catecholamines, on the contrary, were elevated in the elderly. In healthy women during normal menstrual cycle the number of alpha 2-adrenergic receptors decreased with increasing plasma estradiol levels. Incubation of lymphocyte membranes with isoprenaline (100 microM) and of platelet membranes with clonidine (1-100 microM) led to a reduction of the number of beta 2- and alpha 2-receptors, respectively, without changes in the KD-values. Treatment of hypertensive patients with clonidine (3x150 micrograms/die) for 7 days reduced the number of alpha 2-adrenergic receptors in platelets. In platelet membranes from such treated patients inhibition of 3H-yohimbine binding by clonidine and adrenaline was not affected by 10(-4)M GTP. It is concluded, that human alpha- and beta-adrenergic receptors undergo regulatory mechanisms similar to those recently described for adrenergic receptors in a variety of animal models.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D001792:Blood Platelets / Q000378:metabolism; D003000:Clonidine / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism; D005260:Female; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D020120:Iodocyanopindolol; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010646:Phentolamine / Q000494:pharmacology; D010869:Pindolol / Q000031:analogs & derivatives; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015016:Yohimbine / Q000378:metabolism
chemical_list: D004967:Estrogens; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D015016:Yohimbine; D020120:Iodocyanopindolol; D006160:Guanosine Triphosphate; D010869:Pindolol; D003000:Clonidine; D010646:Phentolamine