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Titolo:
COMPARISON OF THE EFFECTS OF INTERNAL [MG2-K1 IN CAT AND GUINEA-PIG CARDIAC VENTRICULAR MYOCYTES(] ON I)
Autore:
MARTIN RL; KOUMI S; EICK RET;
Indirizzi:
NORTHWESTERN UNIV,DEPT PHARMACOL,303 E CHICAGO AVE CHICAGO IL 60611 NORTHWESTERN UNIV,DEPT MOLEC PHARMACOL & BIOL CHEM CHICAGO IL 60611 NORTHWESTERN UNIV,REINGOLD ECG CTR,DEPT MED,DIV CARDIOL CHICAGO IL 60611 NORTHWESTERN UNIV,FEINBERG CARDIOVASC RES INST CHICAGO IL 60611
Titolo Testata:
Journal of Molecular and Cellular Cardiology
fascicolo: 1, volume: 27, anno: 1995,
pagine: 673 - 691
SICI:
0022-2828(1995)27:1<673:COTEOI>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
RECTIFYING POTASSIUM CHANNELS; INWARD RECTIFICATION; ANOMALOUS RECTIFICATION; MAGNESIUM BLOCK; INTRACELLULAR MAGNESIUM; CONDUCTANCE PROPERTIES; CELL-MEMBRANE; ATRIAL CELLS; K+ CHANNELS; HEART-CELLS;
Keywords:
INWARD RECTIFICATION; POTASSIUM CURRENT; ISOLATED CARDIAC VENTRICULAR MYOCYTES; ACTIVATION KINETICS; WHOLE-CELL-PATCH; EXCISED PATCH; PATCH CLAMP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
R.L. Martin et al., "COMPARISON OF THE EFFECTS OF INTERNAL [MG2-K1 IN CAT AND GUINEA-PIG CARDIAC VENTRICULAR MYOCYTES(] ON I)", Journal of Molecular and Cellular Cardiology, 27(1), 1995, pp. 673-691

Abstract

The effects of internal Mg2+ (Mg-i(2+)) on processes underlying the inward rectification of the cardiac I-K1 in enzymatically isolated cardiac ventricular myocytes (CVM) obtained from cat, guinea pig and rabbit were compared using the whole-cell and excised inside-out patch configurations of the voltage-clamp technique. In confirmation of the findings of other investigators, Mg-i(2+)-sensitive outward I-K1 currents could be elicited from guinea pig CVM at 15 degrees C when Mg-i(2+) was reduced from 1 mM to less than 1 mu M, suggesting that Mg-i(2+) has an important role in the inward rectification of I-K1 in guinea pig CVM at unphysiologically low temperatures. However, as temperature was raised to more physiological levels, (e.g., 30 degrees C), Mg-i(2+)-sensitive outward I-K1 currents could no longer be evoked. In contrast with the results obtained with guinea pig CVM, I-K1 remained inwardly rectifying in cat and rabbit CVM independent of the Mg-i(2+) concentration ([Mg2+](i)) at 37 degrees, 15 degrees, 10 degrees and 5 degrees C, Reduced [Mg2+](i) at low temperature (15 degrees C), shifted the voltage dependence of guinea pig I-K1 activation in the depolarizing direction; this resulted in an apparent linearization of I-K1 conductance. When the range of the membrane potential examined was expanded to include voltages up to +80 mV, the guinea pig I-K1 was found to exhibit inward rectification with the inflection in the I-V relationship that is found at similar to E(K) at normal temperature, also shifted 80 mV or more to much less negative voltages at low temperatures. In contrast, irrespective of [Mg2+](i) or temperature, the voltage dependencies of the I-K1 activation curves for both cat and rabbit myocytes were not changed from that defined when [Mg2+](i) was 1 mill and temperature was37 degrees C. We propose that Mg-i(2+) affects inward rectification of I-K1 in cold guinea pig CVM by altering the voltage dependence of activation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/09/20 alle ore 10:51:45