Figure 3. Reciprocal regulation of CCE and NCCE via arachidonic acid and NO.

(a) Increases in [Ca²⁺]_i evoked by AVP (100 nM, open bar) in the presence (i, solid bar) and absence (ii) of extracellular Ca²⁺. (b) Increases in [Ca²⁺]_i recorded 240 s after the addition of AVP (100 nM) are shown for control cells or after pre-treatment with RHC 80267 (50 μM to inhibit DAG lipase), L-NAME (N^G-nitro-L-arginine methyl ester; 700 μM to inhibit NOS) or L-NAME with L-arginine (2.1 mM). Open bars denote responses in the absence of channel blockers, solid bars show responses in the presence of 1 μM Gd³⁺ to inhibit CCE, and hatched bars show responses in the presence of 100 nM SKF 96365 to inhibit NCCE. Results are means±S.E.M for three independent experiments.