Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
H2O2-induced chloride currents are indicative of an endogenous Na(+)-Ca2+ exchange mechanism in Xenopus oocytes.
Schlief T
,
Heinemann SH
.
???displayArticle.abstract???
1. Defolliculated Xenopus oocytes were voltage clamped in bathing solutions containing 115 mM KCl and 1.8 mM CaCl2. External application of H2O2 transiently elicited voltage-dependent outward rectifying currents within several seconds. Upon depolarization to +50 mV these currents had an activation time constant of 370 ms and reached amplitudes of up to 70 microA. This current was also observed in oocytes without the vitelline membrane. 2. The current was abolished by 500 microM niflumic acid, by the replacement of external Cl- by methanesulphonate, or when extracellular Ca2+ was removed indicating the involvement of Ca2+-activated Cl- channels, which are very abundant in Xenopus oocytes. 3. While the current could be recorded in bathing solutions containing Li+, K+, Rb+, Cs+ and NH4+, extracellular Na+ abolished the current completely (IC50 = 6 mM Na+). 4. The H2O2-induced Cl- current was half-maximally blocked by approximately 25 microM 2'4'-dichlorobenzamil, 250 microM MgCl2, 100 microM CdCl2 and 100 microM NiCl2. These substances have been shown to block Na+-Ca2+ exchangers in various tissues. 5. The data are consistent with the existence of an endogenous Na+-Ca2+ exchanger in the plasma membrane of Xenopus oocytes, which runs in reverse mode in the absence of high external Na+ and the presence of external Ca2+. This endogenous component has to be considered when Xenopus oocytes are used for heterologous expression studies.
Aronson,
Kinetic properties of the plasma membrane Na+-H+ exchanger.
1985, Pubmed
Aronson,
Kinetic properties of the plasma membrane Na+-H+ exchanger.
1985,
Pubmed
Barish,
A transient calcium-dependent chloride current in the immature Xenopus oocyte.
1983,
Pubmed
,
Xenbase
Dixon,
Alterations in cardiac membrane Ca2+ transport during oxidative stress.
1990,
Pubmed
Doan,
Hydrogen peroxide activates agonist-sensitive Ca(2+)-flux pathways in canine venous endothelial cells.
1994,
Pubmed
Goldhaber,
Excitation-contraction coupling in single guinea-pig ventricular myocytes exposed to hydrogen peroxide.
1994,
Pubmed
Kaczorowski,
Inhibitors of sodium-calcium exchange: identification and development of probes of transport activity.
1989,
Pubmed
Kaminishi,
Increase vs. decrease of calcium uptake by isolated heart cells induced by H2O2 vs. HOCl.
1989,
Pubmed
Kleyman,
Amiloride and its analogs as tools in the study of ion transport.
1988,
Pubmed
Longoni,
Expression of cardiac sarcolemmal Na+-Ca2+ exchange activity in Xenopus laevis oocytes.
1988,
Pubmed
,
Xenbase
Miledi,
A calcium-dependent transient outward current in Xenopus laevis oocytes.
1982,
Pubmed
,
Xenbase
Parekh,
Ca2+ oscillations and Ca2+ influx in Xenopus oocytes expressing a novel 5-hydroxytryptamine receptor.
1993,
Pubmed
,
Xenbase
Philipson,
Na+-Ca2+ exchange is affected by membrane potential in cardiac sarcolemmal vesicles.
1980,
Pubmed
Reeves,
Redox modification of sodium-calcium exchange activity in cardiac sarcolemmal vesicles.
1986,
Pubmed
Sasaki,
Regulation mechanisms of intracellular pH of Xenopus laevis oocyte.
1992,
Pubmed
,
Xenbase
Shi,
Effects of active oxygen generated by DTT/Fe2+ on cardiac Na+/Ca2+ exchange and membrane permeability to Ca2+.
1989,
Pubmed
Sigel,
mRNA-induced expression of the cardiac Na+-Ca2+ exchanger in Xenopus oocytes.
1988,
Pubmed
,
Xenbase
Supplisson,
A possible Na/Ca exchange in the follicle cells of Xenopus oocyte.
1991,
Pubmed
,
Xenbase
White,
Niflumic and flufenamic acids are potent reversible blockers of Ca2(+)-activated Cl- channels in Xenopus oocytes.
1990,
Pubmed
,
Xenbase
