Fig. 4.
A: perfused SRGs. Glands were perfused with shark Ringer's solution for 30 min under basal conditions with measurements of chloride secretion every 10 min. At 30 min (arrow), 1-min readings were begun and glands were perfused with Ringer's solution containing either CNP (10 nM, n = 5), the PDE-3 inhibitor amrinone (200 μM, n = 4), CNP (10 nM + amrinone 200 μM n = 4), or control basal Ringer's only (n = 12). The chloride secretory response to CNP vs. CNP + amrinone were identical and not additive. Values are mean chloride secretion (μeq·h−1·g−1) ± SE. B: representative Isc experiment in primary culture monolayers of SRG tubular epithelial cells demonstrating an increase in Isc with amrinone, CNP, and forskolin, which was inhibited (9) by bumetanide and BaCl2. The experiment is representative of 4 similar experiments.