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Titolo:
Agonist-independent modulation of L-type Ca currents by basal G(s) proteinactivities in single guinea pig ventricular myocytes
Autore:
Makita, T; Horie, M; Xie, LH; Okada, Y; Sasayama, S;
Indirizzi:
Kyoto Univ, Grad Sch Med, Dept Cardiovasc Med, Div Cardiac Electrophysiol,Sakyo Ku, Kyoto 6068507, Japan Kyoto Univ Kyoto Japan 6068507 trophysiol,Sakyo Ku, Kyoto 6068507, Japan
Titolo Testata:
HEART AND VESSELS
fascicolo: 5, volume: 15, anno: 2000,
pagine: 233 - 239
SICI:
0910-8327(2000)15:5<233:AMOLCC>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
MUSCARINIC K+ CHANNELS; CALCIUM CURRENT; GUANINE-NUCLEOTIDES; ADENYLATE-CYCLASE; CARDIAC MYOCYTES; CA-2+ CURRENT; ION CHANNELS; HEART-CELLS; FORSKOLIN; ACETYLCHOLINE;
Keywords:
adrenergic agonist; Ca channel; G protein; muscarinic agonist; receptor;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Citazioni:
29
Recensione:
Indirizzi per estratti:
Indirizzo: Horie, M Kyoto Univ, Grad Sch Med, Dept Cardiovasc Med, Div Cardiac Electrophysiol,Sakyo Ku, Kyoto 6068507, Japan Kyoto Univ Kyoto Japan 6068507 l,Sakyo Ku, Kyoto 6068507, Japan
Citazione:
T. Makita et al., "Agonist-independent modulation of L-type Ca currents by basal G(s) proteinactivities in single guinea pig ventricular myocytes", HEART VESS, 15(5), 2000, pp. 233-239

Abstract

The modulation of L-type Ca2+ currents (I-Ca,I-L) by the basal activities of G proteins was studied in adult guinea pig ventricular myocytes by whole-cell patch-clamp techniques. With intrapipette guanosine triphosphate (GTP) (100 muM), a specific inhibition of G(i) proteins by pertussis toxin (PTX) produced an increase in the basal density of I-Ca,I-L (from 11.0 +/- 0.8,n = 13, to 25.0 +/- 2.0 pA/pF, n = 11, at 0 mV test potential). In addition, PTX shifted the forskolin (Fsk) concentration-I-Ca,I-L response relationsignificantly leftward (EC50 = 63.7 +/- 12.5 vs 625 +/- 75 nM). With intrapipette guanosine diphosphate (GDP)betaS (1 mM), the Fsk-I-Ca,I-L relation was also shifted leftward (EC50 = 197 +/- 18.3 vs 781 +/- 82.5 nM). However, chronic GDP betaS dialysis accelerated the rundown of I-Ca,I-L significantly, suggesting a potential contribution of G, proteins in maintaining basal I-Ca,I-L. In contrast, intra-pipette GTP gammaS (100 muM) produced a transient rise in I-Ca,I-L from 11.0 +/- 3.0 to 22.8 +/- 7.10 pA/pF (in 3.4 minafter whole-cell formation at 0 mV, n = 9), presumably through the activation of G, proteins. It was followed by a gradual decline in I-Ca,I-L (to 15.5 +/- 3.5 pA/pF), which was still enhanced by Fsk (EC50 = 1450 +/- 98 nM),indicating that the current decay was not solely due to rundown but to activation of G(i) proteins. G(s), in addition to G(i) proteins. show sufficient basal activity to modulate I-Ca,I-L in an agonist-independent manner.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/04/20 alle ore 21:36:47