AJP - Gastrointestinal and Liver Physiology, Vol 269, Issue 2 232-G239, Copyright © 1995 by American Physiological Society

ARTICLES

Transmitter interactions in rabbit internal anal sphincter

M. A. Knudsen, E. B. Glavind and A. Tottrup
Department of Surgical Research 900, University Hospital of Aarhus, Denmark.

The aim of the present study was to investigate the relative importance of the different putative nonadrenergic noncholinergic (NANC) mediators and their interplay with cholinergic nerves in the rabbit internal anal sphincter (IAS). IAS preparations were mounted in organ baths for recording of isometric tension. Transmural field stimulation (TMS; 5-s trains; supramaximal voltage, 140-160 V; 0.4-ms impulse duration) was applied every 2 min with frequencies varying from 0.2 to 32 Hz. TMS induced frequency-dependent relaxations that amounted to 89.3 +/- 2.2% (n = 7). N omega-nitro-L-arginine (L-NNA; 10(-7)-10(-4) M; 8 Hz) reduced relaxations and this effect was partially inhibited by preincubation with L-arginine (10(-4) M). The effect of L-NNA was attenuated by atropine preincubation. Apamin (10(-6) M) shifted the frequency-response curve to the right but left maximal relaxations in response to TMS unaffected. In the presence of L-NNA (10(-4) M) and atropine (10(-6) M), the action (area between the frequency-response curve with or without a substance) of apamin was more pronounced, but, despite the presence of both L-NNA and apamin, some relaxation still remained. The frequency-response curve (control) was significantly shifted to the right by carbachol (10(-6) M). Concentration-response experiments showed that the response to exogenous nitric oxide (NO; 10(-7)-10(-4) M) was unaffected by carbachol (10(-6) M) preincubation, whereas responses to vasoactive intestinal polypeptide (VIP) and ATP were significantly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				B. McDonnell, R. Hamilton, M. Fong, S. M. Ward, and K. D. Keef Functional evidence for purinergic inhibitory neuromuscular transmission in the mouse internal anal sphincter Am J Physiol Gastrointest Liver Physiol, April 1, 2008; 294(4): G1041 - G1051. [Abstract] [Full Text] [PDF]

				L. Hecker, K. Baar, R. G. Dennis, and K. N. Bitar Development of a three-dimensional physiological model of the internal anal sphincter bioengineered in vitro from isolated smooth muscle cells Am J Physiol Gastrointest Liver Physiol, August 1, 2005; 289(2): G188 - G196. [Abstract] [Full Text] [PDF]

				T. Ishiguchi, T. Takahashi, H. Itoh, and C. Owyang Nitrergic and purinergic regulation of the rat pylorus Am J Physiol Gastrointest Liver Physiol, October 1, 2000; 279(4): G740 - G747. [Abstract] [Full Text] [PDF]

				S. Chakder and S. Rattan L-Arginine Deficiency Causes Suppression of Nonadrenergic Noncholinergic Nerve-Mediated Smooth Muscle Relaxation: Role of L-Citrulline Recycling J. Pharmacol. Exp. Ther., July 1, 1997; 282(1): 378 - 384. [Abstract] [Full Text]