Can I read Na+/H+-exchange in A6 cells: Polarity and vasopressin regulation on EtoBox?

Na+/H+-exchange in A6 cells: Polarity and vasopressin regulation by Valeria Casavola; Lorenzo Guerra; Corinna Helmle-Kolb; Stephan J. Reshkin; Heini Murer is a Biochemistry, Genetics and Molecular Biology article available to read on EtoBox.

What is Na+/H+-exchange in A6 cells: Polarity and vasopressin regulation about?

We have analyzed the mechanism of Na(+)-dependent pHi recovery from an acid load in A6 cells (an amphibian distal nephron cell line) by using the intracellular pH indicator 2'7'-bis(2-carboxyethyl)5,6 carboxyfluorescein (BCECF) and single cell microspectrofluorometry. A6 cells were found to express Na+/H(+)-exchange activity only on the basolateral membrane: Na+/H(+)-exchange activity follows simple saturation kinetics with an apparent Km for Na+ of approximately 11 mM; it is inhibited in a competitive manner by ethylisopropylamiloride (EIPA). This Na+/H(+)-exchange activity is inhibited by pharmacological activation of protein kinase A (PKA) as well as of protein kinase C (PKC). Addition of arginine vasopressin (AVP) either at low (subnanomolar) or at high (micromolar) concentrations inhibits Na+/H(+)-exchange activity; AVP stimulates IP3 production at low concentrations, whereas much higher concentrations are required to stimulate cAMP formation. These findings suggest that in A6 cells (i) Na+/H(+)-exchange is located in the basolateral membrane and (ii) PKC activation (heralded by IP3 turnover) is likely to be the mediator of AVP action at low AVP concentrations.

Who reads Na+/H+-exchange in A6 cells: Polarity and vasopressin regulation?

Author

Valeria Casavola; Lorenzo Guerra; Corinna Helmle-Kolb; Stephan J. Reshkin; Heini Murer

Publisher

Springer; Springer-Verlag; Springer Verlag; Springer Science and Business Media LLC (ISSN 0022-2631)

Published

1992

Language

EN

Field

Biochemistry, Genetics and Molecular Biology (Life Sciences)