Effects of prostaglandins on the isolated human minor calyx

Effects of prostaglandins (PGE1, PGE2, PGF2 alpha, and PGI2) on the isolated human minor calyceal strips were isometrically investigated in vitro. PGE2 and PGF2 alpha, 10(-7) to 10(-6) g/ml, increased the basal tone of spontaneous contractions. PGE1 and PGI2 did not affect the contractions of the isolated human minor calyceal strips. The increases on the basal tone induced by PGE2 and PGF2 alpha were not affected by the pretreatment with atropine, hexamethonium, and phentolamine. Following incubation in a Ca2+-free medium, spontaneous contractions and the responses to PGE2 and PGF2 alpha were abolished. The results suggest that the contractile effects of PGE2 and PGF2 alpha may not be mediated by activation of muscarinic, nicotinic, or alpha-adrenergic receptors and result from a consequent increase of the transmembrane Ca2+ influx.