title: Neuronal nitric oxide synthase inhibition and regional sympathetic nerve discharge: implications for peripheral vascular control.
abstract: Neuronal nitric oxide (NO) synthase (nNOS) inhibition with systemically administered S-methyl-l-thiocitrulline (SMTC) elevates mean arterial pressure (MAP) and reduces rat hindlimb skeletal muscle and renal blood flow. We tested the hypothesis that those SMTC-induced cardiovascular effects resulted, in part, from increased sympathetic nerve discharge (SND). MAP, HR, and lumbar and renal SND (direct nerve recordings) were measured in 9 baroreceptor (sino-aortic)-denervated rats for 20min each following both saline and SMTC (0.56mg/kg i.v.). SMTC increased MAP (peak ΔMAP: 50±8mmHg, p<0.01) compared to saline. Lumbar and renal SND were not different between saline and SMTC conditions at any time (p>0.05). The ΔSND between saline and SMTC conditions for the lumbar and renal nerves were not different from zero (peak ΔSND, lumbar: 2.0±6.8%; renal: 9.7±9.0%, p>0.05 versus zero for both). These data support that SMTC-induced reductions in skeletal muscle and renal blood flow reported previously reflect peripheral nNOS-derived NO vascular control as opposed to increased sympathetic vasoconstriction.
authors: Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA. scopp@vet.ksu.edu
authors: Steven W
authors: SW
authors: Copp
authors: Daniel M
authors: DM
authors: Hirai
authors: Gabrielle E
authors: GE
authors: Sims
authors: Richard J
authors: RJ
authors: Fels
authors: Timothy I
authors: TI
authors: Musch
authors: David C
authors: DC
authors: Poole
authors: Michael J
authors: MJ
authors: Kenney
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002956:Citrulline / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000294:innervation; D008161:Lumbosacral Region; D008297:Male; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013127:Spinal Nerves / Q000187:drug effects / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D002956:Citrulline; D052248:Nitric Oxide Synthase Type I; D013890:Thiourea; C086717:S-methylthiocitrulline