Differences in relaxant effects of cyclic GMP on skinned muscle preparations from the proximal and distal colon of rats

Mediators of Nonadrenergic, Noncholinergic Relaxation in Sprague Dawley Rat Intestine: Comparison with the Mediators of Other Strains.

“…However, no participation of VIP in the relaxation was suggested in the distal colon of Sprague Dawley rats and in any regions other than the distal colon of all the three strains. In the present study, effect of VIP [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] was examined on the relaxation induced by EFS only at 10 Hz for 10s, because VIP 10-28 inhibited relaxations of longitudinal muscle of the Wistar-ST rat distal colon induced by EFS at 0.1 and 10 Hz by a similar extent about 45% [15] and the antagonist did not affect the relaxation in Sprague Dawley rats induced by EFS at 10 Hz for longer duration, 20-90 s [21]. The present results indicate that VIP participates NANC relaxation only in the distal colon of Wistar and Wistar-ST, but not Sprague Dawley rats.…”

“…Drugs: Apamin, VIP fragment VIP [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] and N G -nitro-Larginine (N 5 -nitro-amidino-L-2,5-diamino-pentanoic acid: L-NOARG) were purchased from Sigma Chemical Co., ST. Louis, U.S.A. VIP, charybdotoxin, PACAP and its fragment PACAP were purchased from The Peptide Institute, Osaka, Japan. Gaseous nitric oxide was dissolved in Tyrode solution just before experiments, as described by Gillespie and Sheng [4], and added to the organ bath in volumes of 0.3-300 µl.…”

“…Wistar-ST rat intestine is a case in point. That is, an essential role of nitric oxide in the relaxation was suggested in circular [11] and longitudinal [24,26] muscles of the proximal colon, and in circular muscle of the rectum [27], while only minor or no role was suggested in longitudinal muscle of the jejunum [19] or the distal colon [16,24], respectively. In addition to regional difference, we recently found a strain difference in the mediator of NANC relaxation of the distal colon of rats between the Sprague Dawley and Wistar-ST strains: nitric oxide was suggested to partially mediate NANC relaxation of the Sprague Dawley but not Wistar-ST strain [21].…”

Origin of Ca2+ Necessary for Carbachol-Induced Contraction in Longitudinal Muscle of the Proximal Colon of Rats

“…Nitric oxide relaxed longitudinal muscle of the proximal colon precontracted by CCh at 1 mM, but it did not affect that of the distal colon (16). It seems interesting to clarify the reason for the difference in sensitivity of both longitudinal muscles to nitric oxide.…”

Role of the Interstitial Cells Distributed in the Myenteric Plexus in Neural Reflexes in the Mouse Ileum

“…The circular muscle was subjected to a resting load of 0.5 g. The extent of contraction or relaxation was expressed as the area above or under the line of resting tone that was drawn on the bottom of resting spontaneous activity as described elsewhere (13,25). At the end of the experiments, 30 m M papaverine was added to determine the maximum relaxation of the preparation (26,27); the treatment attenuated the spontaneous contractility, turning it to the relaxation that attained the maximum level within approximately 20 min in every preparation.…”