Fig. 7.

Ca dependence of AVP-stimulated CMEC NHE activity measured as HOE-642-sensitive H⁺ flux. CMEC monolayers were exposed to medium containing 0 or 5 μM BAPTA-AM at 37°C for 20 min and then to BAPTA-AM-free medium for 5 min. CMEC were then treated for 5 min with 0 or 100 nM AVP in BAPTA-AM-free medium and finally assayed for 5 min with AVP-containing, BAPTA-AM-free medium. Values are means ± SE of 5 and 6 experiments for control with and without AVP, respectively (both without BAPTA) and 5 and 3 experiments for cells treated with BAPTA with and without AVP, respectively. *Significantly different from control without AVP: P < 0.0001 for control with AVP.