INTRACEREBROVENTRICULARLY INJECTED L-ARGININE-INDUCED VASOPRESSIN RELEASE IS MEDIATED BY CGMP IN RATS

AIM: To study the possible role of cGMP in the effect of L-arginine-in duced arginine-vasopressin (AVP) release. METHODS: In anesthetized rat s, saline, L-arginine, 8-Br-cGMP, L-arginine + methylene blue tan inhi bitor of guanylyl cyclase) were injected intracerebroventricularly (ic v) and the plasma vasopressin level was detected with radioimmunoassay . RESULTS: Both 8-Br-cGMP 2.53 g . L-1 and L-arginine 100 g . L-1 incr eased plasma AVP level [from (2.6 +/- 0.3) to (6.6 +/- 0.4) ng . L-1, and from (3.2 +/- 0.5) to (5.8 +/- 1.4) ng . L-1, respectively; P < 0. 01] 5 min after the icy injection; methylene blue (3.74 g . L-1) + L-a rginine (100 g . L-1) did not change plasma AVP level. CONCLUSION: cGM P was a mediator of the effect of L-arginine-induced AVP release.