Abstract
To determine the cause of dysfunction of colonic movement in patients with Duchenne muscular dystrophy, we studied the effect of selective inhibitor of e-, i- and n-nitric oxide synthase (NOS) on the migrating motor complexes (MMCs) in proximal and distal segments of colon of muscular dystrophy (mdx) mice and compared the findings with those of the control. There was no difference in the frequency of MMCs between the mdx colon and the control; it was 0.58±0.06 (n=9), 0.26±0.04 cpm (n=5) in the mdx proximal and distal segments of colon respectively and 0.72±0.10 (n=6) and 0.29±0.03 cpm (n=7) in the control. The frequency of MMCs was greater in the proximal than the distal segments in both the mdx colon and the control (p<0.01). 1,3-PBIT (inhibitor of i-NOS at low and e-NOS at high dose) and spermine (n-NOS inhibitor) extinguished the MMCs in both the mdx colons and the control. In some quiescent mdx colons and the control, 1,3-PBIT induced the MMCs at a low dose. L-NAME (NOS inhibitor) induced the MMCs in some quiescent mdx colons, but not in the control. The induced MMCs were extinguished by 1,3-PBIT at a high dose or NOC (NO donor). Spermine never induced the MMCs in either the mdx colon or the control. There was no difference in the effect of these NOS inhibitors between the proximal and the distal segments in both the mdx colon and the control. The result suggests that inhibition of i-NOS is more effective than e- and n-NOS in the generation of the MMCs and that the mdx colon is more susceptible to the inhibition of NOS than the control. [Jpn J Physiol 54 Suppl:S123 (2004)]
