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Guanine Nucleotide-Binding Protein, Alpha I-3, Directly Activates A Cation Channel In Rat Renal Inner Medullary Collecting Duct Cells., Douglas B. Light, Dennis A. Ausiello, Bruce A. Stanton

Dartmouth Scholarship

We examined whether GTP binding proteins (G proteins) regulate sodium conducting channels in the apical membrane of renal inner medullary collecting duct (IMCD) cells and thereby modulate sodium absorption. Patch clamp studies were conducted on inside-out patches of the apical membrane of IMCD cells grown in primary culture. Guanosine 5'-triphosphate (GTP) and the nonhydrolyzable GTP analogue, GTP gamma S, which activate G proteins, increased the open probability of the cation channel. In contrast, the nonhydrolyzable GDP analogue, GDP beta S, which decreases G protein activity, inhibited the channel. Pertussis toxin also reduced the open probability of the channel. Addition of …