Nitric oxide synthase in the autonomic nervous system of canine ileum.
The synaptosomes from canine ileal deep muscular plexus possess a nitric oxide (NO)-sensitive soluble guanylate cyclase, as demonstrated by approximately 3- to 4-fold elevation of synaptosomal cyclic GMP levels in the presence of either 1 mM sodium nitroprusside or L-arginine (20-1,000 microM) plus 1 mM NADPH. The activating effect of L-arginine on synaptosomal soluble guanylate cyclase was related to its enzymatic conversion to citrulline by NO synthase. The synaptosomal NO synthase was found to exhibit both calcium-independent and calcium/calmodulin-dependent components accounting for approximately 2- to 2.5-fold and 7- to 8-fold increases in the basal activity, respectively. The absolute magnitude of these activities was several-fold greater compared to the activities observed in the isolated cells of circular smooth muscle. The synaptosomal Ca-independent and Ca/calmodulin-dependent NO synthase activities were inhibited by methylene blue and L-NG-arginine methyl ester. The NO synthase activity was also attenuated in the presence of cyclic AMP (10 microM). Such an inhibition was related primarily to the suppression of Ca-independent activity. The ability of enteric nerves to generate NO from L-arginine strongly suggests the involvement of this process in the biochemical mechanisms underlying the neurogenic control of intestinal motility.
Kostka
P
P
Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
Jang
E
E
Watson
E G
EG
Stewart
J L
JL
Daniel
E E
EE
D000594:Amino Acid Oxidoreductases / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000201:enzymology* / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D002956:Citrulline / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004285:Dogs; D006162:Guanylate Cyclase / Q000378:metabolism; D007082:Ileum / Q000201:enzymology / Q000294:innervation*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000201:enzymology / Q000294:innervation; D019331:NG-Nitroarginine Methyl Ester; D009469:Neuromuscular Junction / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology; D019001:Nitric Oxide Synthase; D013347:Subcellular Fractions / Q000201:enzymology; D013574:Synaptosomes / Q000201:enzymology / Q000378:metabolism; D014316:Tritium
D014316:Tritium; D002956:Citrulline; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester