Pertussis toxin abolishes angiotensin II-induced phosphoinositide hydrolysis and prostaglandin synthesis in rat renal mesangial cells

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Abstract
Incubation of rat renal mesangial cells with angiotensin II (0.1 .mu.M) resulted in transient breakdown of phosphatidylinositol 4,5-bisphosphate, rapid generation of diacylglycerol and phosphatidic acid, increased 45Ca2+ influx, increased intracellular [Ca2+] as measured by quin 2, and increased prostaglandin E2 synthesis. All of these processes were markedly inhibited time- and dose-dependently by prior exposure of cells to pertussis toxin. In contrast, the effects of the ionophore A23187 on 45Ca2+ influx and prostaglandin E2 synthesis were not altered by the exposure of the cells to pertussis toxin. The action of the toxin was not associated with alterations in cellular concentrations of cyclic AMP. Incubation of membrane fraction of mesangial cells with pertussis toxin resulted in ADP-ribosylation of Mr-42000 protein. From all these results, it is likely that a G protein is involved in receptor-mediated signal transduction in renal mesangial cells.