Figure 5.

Concentration-dependent inhibition of cGKII-dependent anion secretion in mouse ileum by AP-C5 and AP-C6. A, representative Ussing chamber experiment illustrating the procedure for testing inhibition of cGKII-dependent, CFTR-mediated anion secretion. Anion secretion was stimulated by addition of 8-pCPT-cGMP. After the ensuing Isc response had reached a plateau, compound or vehicle (DMSO) was added to the luminal bath. Inhibition of ileal anion secretion was calculated as the reduction in the Isc response 20 min after addition of compound relative to the initial full Isc response assessed just before addition of the compound. B, inhibition of 8-pCPT-cGMP–dependent anion secretion as a function of compound concentration. Data of six (AP-C5) or five (AP-C6) biological replicates were analyzed by nonlinear regression, yielding the IC₅₀ values (mean with 95% confidence interval in square brackets) shown in the inset. Error bars represent S.D.