title: The peripheral platelet count in response to adrenergic alpha-and beta-1-receptor stimulation.
abstract: The aim of the present work was to investigate the effect of adrenergic alpha- and beta-1-receptor stimulation on the peripheral platelet count. The experiments were carried out on 8 healthy male volunteers using radioisotopically labelled platelets. 3 subjects received i.v. infusions of adrenaline (0.09 microgram X kg-1 X min-1) before and after the ingestion of 40 mg propranolol. In response to the first infusion there was an instant increase in the venous platelet-bound radioactivity (PBR) which amounted to 12% over basal value. This effect of adrenaline seemed to be potentiated by propranolol pretreatment. 5 subjects received i.v. infusions of the highly selective beta-1-receptor agonist H 133/22 (prenalterol, Hässle, Sweden). In response to a cumulative dose of 4.75 mg prenalterol a slight but significant (P less than 0.05) decrease in PBR occurred. It is concluded that alpha-receptor stimulation causes a depletion of platelets from the exchangeable splenic platelet pool resulting in a concomitant increase in the peripheral platelet count. Beta-receptor stimulation has an opposite effect on the spleen. The trapping of platelets by the spleen is mediated both via beta-1- and beta-2-receptors, but the effect of beta-2-receptor stimulation seems to predominate.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000328:Adult; D001772:Blood Cell Count; D001792:Blood Platelets; D001794:Blood Pressure / Q000187:drug effects; D002452:Cell Count / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D011433:Propranolol / Q000494:pharmacology
chemical_list: D000318:Adrenergic beta-Agonists; D011433:Propranolol; D004837:Epinephrine