title: Age-dependent decrease of alpha 2-adrenergic receptor number in human platelets.
abstract: In 36 healthy subjects of various ages (14-76 years) the number of alpha 2-adrenergic receptors in platelets - as determined by [3H]yohimbine binding - and plasma catecholamine levels were measured. A highly significant negative correlation (r = -0.666, P less than 0.001) between the number of alpha 2-adrenergic receptors and age was found; on the contrary, plasma catecholamine concentrations increased with increasing age. Thus, reduced responses in the elderly to adrenergic stimuli may be due to reduced number of adrenergic receptors.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001792:Blood Platelets / Q000032:analysis*; D002395:Catecholamines / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011941:Receptors, Adrenergic / Q000032:analysis*; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D015016:Yohimbine / Q000378:metabolism
chemical_list: D002395:Catecholamines; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine