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Title: Regulation of hormone-induced Ca sup 2+ mobilization in the human platelets

{alpha}-Thrombin, {gamma}-thrombin, and platelet-activating factor each stimulated the mobilization of intracellular Ca{sup 2+} stores in aspirin-treated human platelets. This was followed by desensitization of the receptors, as shown by the return of the Ca{sup 2+} level to basal values and by the fact that a subsequent addition of a second different agonist, but not the same agonist, could again elicit a response. Epinephrine, acting on {alpha}{sub 2}-adrenergic receptors, was by itself ineffective at mobilizing Ca{sup 2+} stores. However, when added after the thrombin-induced response, epinephrine could evoke a considerable release of Ca{sup 2+} from cellular stores. This appeared to be due to epinephrine recoupling thrombin receptors to phospholipase C. In support of this, epinephrine was able to induce the formation of inositol triphosphate when added after the response to thrombin had also become desensitized. Alone, epinephrine was without effect. Pre-activation of protein kinase C with the phorbol ester abolished these effects of epinephrine, suggesting that epinephrine was working by activating a protein which could be inactivated by phosphorylation. The current work is to characterize this protein that may be a member of the G{sub i}, GTP-binding protein family.
Authors:
;  [1]
  1. (Burroughs Wellcome Co., Research Triangle Park, NC (USA))
Publication Date:
OSTI Identifier:
5393803
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Health Perspectives; (United States); Journal Volume: 84
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CALCIUM COMPOUNDS; MEMBRANE TRANSPORT; PHORBOL ESTERS; BIOLOGICAL EFFECTS; PHOSPHOTRANSFERASES; ENZYME INDUCTION; ADRENALINE; BLOOD PLATELETS; INOSITOL; MAN; THROMBIN; TRITIUM COMPOUNDS; ADRENAL HORMONES; ALKALINE EARTH METAL COMPOUNDS; ANIMALS; AUTONOMIC NERVOUS SYSTEM AGENTS; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BLOOD COAGULATION FACTORS; BODY FLUIDS; CARBOHYDRATES; CARCINOGENS; CARDIOTONICS; CARDIOVASCULAR AGENTS; COAGULANTS; DRUGS; ENZYMES; ESTERS; GENE REGULATION; HEMATOLOGIC AGENTS; HEMOSTATICS; HORMONES; HYDROGEN COMPOUNDS; HYDROLASES; INOSITOLS; MAMMALS; MATERIALS; MONOSACCHARIDES; NEUROREGULATORS; ORGANIC COMPOUNDS; PEPTIDE HYDROLASES; PHOSPHORUS-GROUP TRANSFERASES; PRIMATES; PROTEINS; SACCHARIDES; SERINE PROTEINASES; SYMPATHOMIMETICS; TRANSFERASES; VERTEBRATES 550201* -- Biochemistry-- Tracer Techniques