Role of Nitric Oxide in Desmopressin-Induced Vasodilation of Microperfused Rabbit Afferent Arterioles

We have previously reported that desmopressin (dDAVP) increased the lumen diameter of norepinephrine (NE)-constricted isolated microperfused rabbit afferent arterioles. In this study, we examined the role of nitric oxide in dDAVP-induced vasodilation of afferent arterioles. We microdissected a superficial afferent arteriole from the kidney of a New Zealand white rabbit. Each afferent arteriole was cannulated with a pipette system and microperfused in vitro at 60mmHg. dDAVP increased the lumen diameter of NE-preconstricted rabbit afferent arterioles dose-dependently. dDAVP-induced vasodilation was abolished by pretreatment with NG-nitro-L-arginine (L-NNA, 10-4M) (L-NNA+NE, 6.7±1.1μm; L-NNA+NE+dDAVP, 7.3±1.4μm, n=8). dDAVP increased the lumen diameter of NE-preconstricted afferent arterioles pretreated with L-NNA and L-arginine (10-2M) (L-NNA+L-arginine+NE, 6.1± 1.1μm; L-NNA+L-arginine+NE+dDAVP, 8.7±0.9μm*; * p