Effect of pertussis toxin on parathyroid hormone-stimulated cyclic AMP production in cultured kidney cells

Abstract

The effect of pertussis toxin, which inactivates the guanine nucleotide binding regulatory proteins G_i and G_o on cAMP production in response to parathyroid hormone PGE₂ or forskolin, was examined in confluent opossum kidney (OK) cells. This effect was compared with that caused by dexamethasone. The response to PTH was increased in cells preincubated with either agent. The effect of pertussis toxin was selective for PTH, since cAMP production in response to neither PGE₂ nor forskolin was increased. In contrast, the response to forskolin was enhanced in dexamethasone-treated cells. These results indicate that both stimulatory and inhibitory guanine nucleotides binding regulatory proteins modulate PTH-induced cAMP producion in OK cells. Moreover, pertussis toxin and dexamethasone appear to affect different levels of the PTH-receptor-adenylate cyclase complex.