Opposing effects of aluminum on inward-rectifier potassium currents in bean root-tip protoplasts.

Autor:	Etherton, B, Heppner, T J, Cumming, J R, Nelson, M T
Předmět:	POTASSIUM metabolism PLANT root physiology SODIUM metabolism ALUMINUM BIOLOGICAL transport CELL culture CELLS CELLULAR signal transduction COMPARATIVE studies DRUG resistance IMMUNITY RESEARCH methodology MEDICAL cooperation PLANTS POTASSIUM RESEARCH RESEARCH funding PLANT roots EVALUATION research PHYSIOLOGY
Zdroj:	Journal of Membrane Biology; Mar2004, Vol. 197 Issue 3, p15-22, 8p
Abstrakt:	Inward currents in root cap protoplasts of the aluminum-tolerant cultivar, Dade, of Phaseolus vulgaris L. were investigated using the whole-cell patch-clamp technique. The properties of these currents were similar to those seen in inward rectifying K+ channels in other plant tissues. Replacing bath K+ with Na+ nearly abolished the observed currents. Higher bath K+ concentrations increased inward currents. AlCl3 in pH 4.7 bath solutions caused inward K+ currents to activate more rapidly and at more positive voltages when compared with AlCl3 free solutions. In 10 microM AlCl3 the activated inward K+ currents were significantly larger than in the AlCl3-free solution at all voltages except at the most negative voltage of -174 mV and the least negative of -74 mV. In contrast, in 80 microM Al3+, when hyperpolarizing voltages were most negative, the inward K+ currents were inhibited relative to the currents in 10 microM AlCl3. Enhancement of inward K+ currents by AlCl3 is consistent with Al3+ binding to the external surface of the root cap protoplast, decreasing the surface charge, thus causing the channels to sense a more negative membrane potential. Inhibition of inward K+ currents with higher AlCl3 concentrations and more negative voltages is consistent with Al3+ block of K+ channels. [ABSTRACT FROM AUTHOR]
Databáze:	Complementary Index
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