EFFECT OF PURINERGIC STIMULATION ON INTRACELLULAR CALCIUM-CONCENTRATION AND TRANSEPITHELIAL POTENTIAL DIFFERENCE IN CULTURED BOVINE OVIDUCTCELLS

Epithelial cells were removed from bovine oviducts by enzyme digestion and either cultured on laminin-coated coverslips (for determination o f [Ca2+](i)) or on collagen filters (for determination of transepithel ial potential differences [pd]). Cells on coverslips were loaded with Fura-2 to monitor [Ca2+](i). Application of extracellular ATP induced a transient increase in [Ca2+](i) in a dose-dependent manner. This res ponse was abolished by thapsigargin, indicating that the rise in [Ca2](i) was derived from intracellular stores. The order of potency of th e nucleotide-induced rise in [Ca2+](i) was uridine triphosphate (UTP)> ATP>ADP. Epithelial cells were grown on collagen filters, and when mou nted in a modified Ussing chamber exhibited an electrical pd of 1.00 /- 0.36 mV with the apical side negative with respect to the basal. Ap plication of UTP, ATP, and ADP to the basal side induced transient inc reases in pd of 1.15 +/- 0.21, 0.77 +/- 0.16, and 0.26 +/- 0.06 mV, re spectively. The order of potency of the nucleotides in eliciting trans ient increases in [Ca2+](i) and pd suggests the presence of a P-2u pur inergic receptor in the bovine oviduct epithelium that could play a ro le in transepithelial ion movements and hence the control of oviductal fluid formation.