Phospholamban and troponin I are substrates for protein kinase C in vitro but not in intact beating guinea pig hearts

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Circulation Research (An Official Journal of the American Heart Association); (USA)

DOI:https://doi.org/10.1161/01.RES.67.2.394· OSTI ID:6528677

Edes, I; Kranias, E G ^[1]

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1. Univ. of Cincinnati College of Medicine, OH (USA)

The incorporation of (32P)inorganic phosphate into membranous, myofibrillar, and cytosolic proteins was studied in Langendorff-perfused guinea pig hearts treated with phorbol 12-myristate 13-acetate (PMA) or 1,2-dioctanoylglycerol (D8G), which are potent activators of protein kinase C. Control hearts were perfused with an inactive phorbol ester (4 alpha-phorbol 12,13-didecanoate), which does not cause activation of protein kinase C. To ensure the blockade of different receptor systems, the perfusions were carried out in the presence of prazosin, propranolol, and atropine. Perfusion of hearts with either PMA (4 microM) or D8G (200 microM) was associated with a negative effect on left ventricular inotropy and relaxation. Examination of the 32P incorporation into various fractions revealed that there were no increases in the degree of phosphorylation of phospholamban in sarcoplasmic reticulum, and troponin I and C protein in the myofibrils, although these proteins were found to be substrates for protein kinase C in vitro. However, in the same hearts, there were significant changes in the 32P incorporation into a 28-kDa cytosolic-protein. Examination of the activity levels of protein kinase C in hearts perfused with PMA indicated a redistribution of this activity from the cytosolic to the membrane fraction, suggesting the activation of the enzyme in vivo. These findings indicate that cardiac regulatory phosphoproteins, which may be phosphorylated by protein kinase C in vitro, are not substrates for protein kinase C in beating hearts perfused with phorbol esters or diacylglycerol analogues.

• OSTI ID: 6528677
• Journal Information: Circulation Research (An Official Journal of the American Heart Association); (USA), Journal Name: Circulation Research (An Official Journal of the American Heart Association); (USA) Vol. 67:2; ISSN CIRUA; ISSN 0009-7330
• Country of Publication: United States
• Language: English

Related Subjects

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560300 -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALINE EARTH METALS
AMP
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BODY
CALCIUM
CARCINOGENS
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENDOPLASMIC RETICULUM
ENZYME ACTIVITY
ENZYMES
ESTERS
GUINEA PIGS
HEART
IN VITRO
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPIDS
MAMMALS
MEMBRANES
METALS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANOIDS
ORGANS
PERFUSED ORGANS
PHORBOL ESTERS
PHOSPHOLIPIDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
RADIOISOTOPES
RODENTS
SARCOPLASMIC RETICULUM
SUBSTRATES
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES