Pertussis toxin inhibits the angiotensin II and serotonin-induced rise of free cytoplasmic calcium in cultured smooth muscle cells from rat aorta.

Angiotensin II, serotonin and K+-depolarization cause an increase in free cytoplasmic Ca2+ in cultured smooth muscle cells. The involvement of a guanine nucleotide-binding protein has been investigated by using pertussis toxin. When smooth muscle cells were pretreated with pertussis toxin angiotensin II and serotonin-induced rise of cytosolic Ca2+ was found to be significantly reduced whereas the Ca2+ influx mediated by K+-depolarization remained unchanged. These results suggest the participation of a guanine nucleotide-binding protein in the receptor-mediated rise of intracellular Ca2+.