Pelvic nerve stimulation evokes nitric oxide mediated distal rectal relaxation in pigs.
OBJECTIVE
Pelvic nerve stimulation evokes a complex motility response in the pig rectum with a proximal decrease and a distal increase in cross-sectional area. This study investigated whether the distal increase in the cross-sectional area is because of smooth muscle relaxation mediated by nitric oxide.


METHODS
The pelvic nerves were stimulated with cuff electrodes in ten chloralose-anesthetized minipigs. Pressure, volume, and cross-sectional areas at five positions in the rectum were obtained during stimulation to examine the effect of N(G)-nitro-L-arginine (an inhibitor of nitric oxide synthase) injection.


RESULTS
Stimulation evoked a median pressure decrease of 13 cm H(2)O (range, 0-27; P < 0.05; n = 10) in the anal canal, a pressure increase of 6 cm H(2)O (range,-15 to 30; P < 0.05; n = 10) in the rectum and a decrease of 39 mL (range, 30-63; P < 0.05; n = 6) in rectal volume. Rectal cross-sectional areas decreased 33 percent (range, 5-56; P < 0.02; n = 7) in the proximal part and increased 32 percent (range, 9-67; P < 0.02; n = 8) in the distal part. N(G)-nitro-L-arginine eliminated the increase in the distal rectal cross-sectional area (n = 5) and the decrease in anal canal pressure (n = 9) in all tested animals.


CONCLUSIONS
Pelvic nerve stimulation evokes distal rectal relaxation in pigs, sensitive to N(G)-nitro-L-arginine, which suggests that this smooth muscle response is mediated by nitric oxide.
Surgical Research Unit, Department of Surgery P, Aarhus University Hospital, Aarhus, Denmark. fvm@ki.au.dk
Flemming V
FV
Møller
Steen
S
Buntzen
Nico J M
NJ
Rijkhoff
Søren
S
Laurberg
D001003:Anal Canal / Q000294:innervation* / Q000502:physiology; D000818:Animals; D004558:Electric Stimulation; D005260:Female; D009130:Muscle, Smooth / Q000294:innervation* / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D011312:Pressure; D012007:Rectum / Q000294:innervation* / Q000502:physiology; D013552:Swine; D013556:Swine, Miniature; D019323:omega-N-Methylarginine / Q000494:pharmacology
D019323:omega-N-Methylarginine; D009569:Nitric Oxide