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Titolo:
ALPHA(1)-ADRENERGIC STIMULATION OF PHOSPHOLIPASE-C ACTIVITY IN PURIFIED CARDIAC SARCOLEMMAL MEMBRANES
Autore:
MEIJ JTA; DHALLA V; PANAGIA V;
Indirizzi:
UNIV MANITOBA,ST BONIFACE GEN HOSP,FAC MED,RES CTR,DIV CARDIOVASC SCI,351 TACHE AVE WINNIPEG MB CANADA UNIV MANITOBA,ST BONIFACE GEN HOSP,FAC MED,RES CTR,DIV CARDIOVASC SCIWINNIPEG MB CANADA UNIV MANITOBA,FAC MED,DEPT ANAT WINNIPEG MB CANADA
Titolo Testata:
Receptor
fascicolo: 2, volume: 4, anno: 1994,
pagine: 109 - 119
SICI:
1052-8040(1994)4:2<109:ASOPAI>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIVER PLASMA-MEMBRANES; GTP-GAMMA-S; INOSITOL TRISPHOSPHATE; G-PROTEINS; PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE; ALPHA-1-ADRENERGIC RECEPTOR; 2ND MESSENGERS; ACTIVATION; PURIFICATION; HEART;
Keywords:
PHOSPHOLIPASE C; PHOSPHOINOSITIDES; PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE; ALPHA(1)-ADRENOCEPTOR; HEART; SARCOLEMMAL MEMBRANES; G PROTEIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
J.T.A. Meij et al., "ALPHA(1)-ADRENERGIC STIMULATION OF PHOSPHOLIPASE-C ACTIVITY IN PURIFIED CARDIAC SARCOLEMMAL MEMBRANES", Receptor, 4(2), 1994, pp. 109-119

Abstract

Cardiac sarcolemmal (SL) phospholipase C (PLC) is a key enzyme in thesignal transduction of several cardiac receptors. Thus, the earlier described Ca2+-stimulated SL PLC activity may represent variously coupled enzymes. The present study was undertaken to delineate the alpha(1)-adrenoceptor/G protein-stimulated PLC activity in purified cardiac SLvesicles. Although certain detergents and membrane pore formers enhanced SL PLC activity, measured as formation of H-3-inositol 1,4,5-trisphosphate [Ins(1,4,5)P-3] from H-3-phosphatidylinositol 4,5-bisphosphate, alpha(1)-adrenoceptor stimulated activity was not observed. When SLvesicles were preincubated (0-4 degrees C) with substrate in detergent-free buffer, subsequent incubation (37 degrees C; in mM: 100 NaCl, 2EGTA, 1.8 CaCl2, 10 LiCl) resulted in a time-dependent production of H-3-Ins(1,4,5)P-3, that was increased in the presence of 100 mu M GTP gamma S. GTP gamma S stimulation of SL PLC activity required the presence of Mg2+ and Ca2+, but was lost at (sub)millimolar concentrations of these bivalent cations. Mg2+ (0.01-10 mM) promoted a 2,3-diphosphoglycerate-insensitive phosphatase activity. GTP gamma S enhanced the sensitivity of SL PLC to Ca2+, but did not increase the maximum Ca2+ (0.1-1 mM) stimulated SL PLC activity. At 5 mu M Ca2+, GTP gamma S induceda concentration-dependent rise in inositol phosphates production, which was further elevated by the alpha(1)-agonist, phenylephrine (PhE). The PhE-effect was inhibited by the alpha(1)-antagonist prazosin, but not by the beta-antagonist atenolol. These results show that the components necessary for the alpha(1)-adrenoceptor transmembrane signal areassociated with the SL membrane and can be functionally coupled.

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Documento generato il 04/12/20 alle ore 03:49:33