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Title: Phorbol ester stimulates membrane association of protein kinase C and inhibits spontaneous Ca/sup 2 +/ dependent sarcoplasmic reticulum Ca/sup 2 +/ release in rat cardiac cells

Spontaneous oscillatory Ca/sup 2 +/ release from sarcoplasmic reticulum (SR) occurs in rat cardiac myocytes at hyperpolarized membrane potentials and is manifested as contractile waves (W). W frequency varies with SR functional status and cell Ca/sup 2 +/ loading. In myocyte suspensions (Hepes buffer, 37/sup 0/C (Ca/sup 2 +/) = 1.0mM) phorbol myristate acetate, PMA, (10/sup -7/ M) increased protein kinase C activity in membranes as a fraction of total (PKCAM) fivefold with a t 1/2 of < 30 sec (n = 3) and decreased W frequency in individual myocytes (n = 8). This effect varied directly and linearly with baseline W frequency, r = .94, p < .001). Dioctanoyl glycerol (10 ..mu.. M) had a similar effect on W. The PMA effect to decrease W frequency could be a direct one on SR or result from a reduction in cell Ca/sup 2 +/. The time course of PKCAM change is sufficiently rapid for it to mediate the effect on W. Thus, enhanced PKCAM may exert negative feedback control on Ca/sup 2 +/ mobilization during ..cap alpha..-adrenergic stimulation.
Authors:
; ; ; ; ;
Publication Date:
OSTI Identifier:
5422312
Report Number(s):
CONF-8604222-
Journal ID: CODEN: FEPRA
Resource Type:
Conference
Resource Relation:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States); Journal Volume: 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
Research Org:
Gerontology Research Center, Baltimore, MD
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; CALCIUM; MEMBRANE TRANSPORT; PHORBOL ESTERS; BIOLOGICAL EFFECTS; PHOSPHOTRANSFERASES; ENZYME ACTIVITY; CELL MEMBRANES; HEART; RATS; ALKALINE EARTH METALS; ANIMALS; BODY; CARCINOGENS; CARDIOVASCULAR SYSTEM; CELL CONSTITUENTS; ELEMENTS; ENZYMES; ESTERS; MAMMALS; MEMBRANES; METALS; ORGANIC COMPOUNDS; ORGANS; PHOSPHORUS-GROUP TRANSFERASES; RODENTS; TRANSFERASES; VERTEBRATES 560301* -- Chemicals Metabolism & Toxicology-- Cells-- (-1987)