Figure 4.

Calcium dependence of BK-stimulated IPs accumulation in TECs. Cells were incubated either in KHS, Ca²⁺-free KHS, Ca²⁺-free KHS plus 0.5 mM EGTA, Ni²⁺ (5 mM), nifedipine (10 μM), verapamil (10 μM) or diltiazem (10 μM) with 10 mM LiCl for 30 min. Then BK (10 μM) was added and continuously incubated at 37°C for 60 min. [³H]-IPs were determined as described under Methods. Values represent mean±s.e.mean of triplicate determinations in three separate experiments. ^*P<0.001, as compared with that of cells treated with BK alone in KHS buffer. The basal level of IPs accumulation was 17350±1670 d.p.m. well.⁻¹