The effect of e-, i-, and n-nitric oxide synthase inhibition on colonic motility in normal and muscular dystrophy (mdx) mice.
To explore the origin of diarrhea or constipation in human Duchenne muscular dystrophy (DMD), the effect of the inhibition of e- , i-, and n-nitric oxide synthase (NOS) on the motility of proximal and distal segments of colon of muscular dystrophy (mdx) and control mice was studied. The frequency of migrating motor complexes (MMC) was higher in the proximal than in the distal segments in mdx colon (0.56 vs. 0.25 cpm) and in the control colon (0.7 vs. 0.25 cpm), and there was no difference when mdx was compared to control segments. High concentrations of NOS inhibitors, including 1,3-PBIT dihydrobromide (1,3-PBIT) and spermine, inhibited MMC. The dose of spermine required to inhibit MMC was lower for the proximal mdx colon than for the distal mdx or control colon. In the presence of tetrodotoxin, spermine (1 mM) and 1,3-PBIT (5 mM) reduced the magnitude of local, rhythmic contractions (LC) paced by the interstitial cells of Cajal (ICC), but 1,3-PBIT (50 microM) increased their magnitude. There was no difference in the effect of spermine and 1,3-PBIT on the LC between mdx and control colon. The results suggest an inhibition of MMC by high concentrations of e-, i-, and n-NOS inhibitors, modulation of ICC activity by e-NOS, and greater susceptibility of MMC to n-NOS inhibition in the mdx proximal than in the control colon, which is very likely because of a deficit in n-NOS in the mdx smooth muscle affecting the MMC pacemaker. A deficit in the effect of mdx smooth muscle n-NOS on an MMC pacemaker may be the origin of diarrhea or constipation in human DMD.
Tameyasu
Tsukasa
T
Department of Physiology, St. Marianna University School of Medicine, Kawasaki 216-8511, Japan. t2tame@marianna-u.ac.jp
Ogura
Seiko
S
Ogihara
Kyoko
K
D000818:Animals; D003106:Colon / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology*; D018738:Hexamethonium / Q000494:pharmacology; D008297:Male; D051379:Mice; D018101:Mice, Inbred mdx; D020388:Muscular Dystrophy, Duchenne / Q000201:enzymology / Q000503:physiopathology; D016065:Myoelectric Complex, Migrating / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009603:Nitroso Compounds / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology
D004791:Enzyme Inhibitors; C118603:NOC 12; D009419:Nerve Tissue Proteins; D009603:Nitroso Compounds; C118852:S,S'-1,4-phenylene-bis(1,2-ethanediyl)bis-isothiourea; D013096:Spermine; D018738:Hexamethonium; D013779:Tetrodotoxin; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496321:Nos1 protein, mouse; C496317:Nos2 protein, mouse; C496315:Nos3 protein, mouse; D013890:Thiourea; D019331:NG-Nitroarginine Methyl Ester