Effects of intracellular Ca2+ increase by CPA on contractions by PE in the presence of diltiazem or 2-APB.
A) Representative example of PE-induced contractions after incubation of a segment with 35 μM diltiazem (red) or 50 μM 2-APB (green). 10 μM CPA was added in both conditions as indicated, after which 50 μM 2-APB (arrow, +2-APB)was added to the diltiazem condition and diltiazem (arrow, +dil) to the 2-APB condition. Figure B summarizes the results (n = 5). In C, the segments were incubated with 50 μM 2-APB and 35 μM diltiazem before the challenge with 1 μM PE. Subsequent addition of 10 μM CPA did not increase the PE-induced contraction. Part D summarizes the results with the change in isometric force by the diltiazem/2-APB in baseline conditions or following addition of 1 μM PE alone (PE) or in combination with 10 μM CPA (PE+CPA) (n = 4).*, **: p<0.05, 0.01 2-APB versus diltiazem condition in B or PE/PE+CPA versus baseline in D.