The Importance of Refractoriness in Ovine Antral Digestive and Interdigestive Motility

The aim of this work was to find possible differences between the effects of anticholinergic drug administration during the duodenal phase 1 or phase 2a of migrating myoelectric complex on antral spike burst amplitude in fasted and non-fasted sheep. Eight adult rams possessing bipolar electrodes in the antrum and small intestine were used in the study. Feeding increased significantly the spike burst amplitude range from 60-110 to 80-160 µV. The effects of hexamethonium (2 mg/kg), atropine (0.1 mg/kg) and pirenzepine (0.5 mg/kg) given i.v. during phase 1 of the migrating myoelectric complex (expressed as per cent of control) in non-fasted sheep were 68 ± 18, P < 0.05, 69 ± 20, P < 0.05, 45 ± 18, P < 0.01, respectively. The effects of the same doses of these drugs given during phase 2a of the migrating myoelectric complex in non-fasted sheep were 54 ± 13, P < 0.01, 41 ± 12, P < 0.0001, 33 ± 11, P < 0.0001, respectively. In non-fasted animals, the anticholinergic drugs exerted a more pronounced effect than in fasted animals. These effects were partially dose-dependent. The effects of drug combinations were not additive. It is concluded that the effects of anticholinergic substances given during phase 1 or 2a of migrating myoelectric complex and under various feeding conditions on ovine antral spike burst amplitude can vary, partially due to the intensity of the refractory period.

Anahtar Kelimeler:

Sheep, abomasal antrum, myoelectric activity, feeding, anticholinergic drugs

The Importance of Refractoriness in Ovine Antral Digestive and Interdigestive Motility

Keywords:

Sheep, abomasal antrum, myoelectric activity, feeding, anticholinergic drugs,

PDF

___

Plaza, M.A., Arruebo, M.P., Sopena, J., Bonafonte, J.I., Murillo,
M.D.: Myoelectrical activity of the gastrointestinal tract of sheep
analysed by computer. Res. Vet. Sci., 1996; 60: 55-60. 5.
Plaza, M.A., Arruebo, M.P., Murillo, M.D.: Effect of motilin,
somatostatin and bombesin on gastroduodenal myoelectric
activity in sheep. Life Sci., 1996; 58: 1413-1423. 6.
Ruckebusch, Y., Malbert, C.H., Crichlow, E.C.: Hexamethonium:
a probe to assess autonomic nervous system involvement in upper
gastrointestinal functions in conscious sheep. Vet. Res. Commun.,
; 11: 293-303. 7. Roma´nski, K.W.: Antral myoelectric activity in sheep: the effect of feeding and anticholinergic drug administration during various phases of migrating myoelectric complex. Acta Vet. Beograd, 2002; 52: 235-248. 8. Code, C.F., Marlett, J.A.: The interdigestive myoelectric complex of the stomach and small bowel of dogs. J. Physiol., 1975; 246: 289-309. 9. Dent, J., Dodds, W.J., Sekiguchi, T., Hogan, W.J., Arndorfer, R.C.: Interdigestive phasic contractions of the human lower esophageal sphincter. Gastroenterology, 1983; 84: 453-460.
Roma´nski, K.W.: Characteristics and cholinergic control of the ‘minute rhythm’ in ovine antrum, small bowel and gallbladder. J. Vet. Med., A, 2002; 49: 313-320.
Snedecor, G.W., Cochran, W.G.: Statistical Methods. The Iowa State University Press, Ames 1971.
Bueno, L., Fioramonti, J.: Rhythms of abomaso-intestinal motility. In: Y. Ruckebusch, P. Thivend, eds. Digestive Physiology and Metabolism in Ruminants. MTP Press Ltd. Lancaster 1980, pp. 53-80.
Gregory, P.C., Miller, S.J., Brewer, A.C.: The relationship between food intake and abomasal emptying and small intestinal transit time in sheep. Br. J. Nutr., 1985; 53: 373-380.
Lang, I.M., Sarna, S.K., Condon, R.E.: Generation of phases I and II of migrating myoelectric complex in the dog. Am. J. Physiol., 1986; 251: G201-G207.
Sarna, S., Northcott, P., Belbeck, L.: Mechanism of cycling of migrating myoelectric complexes: effect of morphine. Am. J. Physiol., 1982; 242: G588-G595.
Sarna, S.K., Daniel, E.E.: Threshold curves and refractoriness properties of gastric relaxation oscillators. Am. J. Physiol., 1974; 226: 749-755.
Lester, G.D., Bolton, J.R.: Effect of dietary composition on abomasal and duodenal myoelectrical activity. Res. Vet. Sci., 1994; 57: 270-276.
Davenport, H.W.: Physiology of the Digestive Tract. An Introductory Text. Year Book Medical Publishers, Inc. Chicago 1982.
Ooms, L.A.A., Weyns, A., Degryse, A., Ruckebusch, Y.: Pharmacology of the (fore)-stomach smooth muscles. In: A.S.J.P.A.M. Van Miert, M.G. Bogaert, M. Debackere, eds. Comparative Veterinary Pharmacology, Toxicology and Therapy. MTP Press Ltd. 1986, pp. 107-121.
De Vos, W.C.: Role of the enteric nervous system in the control of migrating spike complexes in the feline small intestine. Am. J. Physiol., 1993; 265: G628-G637.
Nakazato, Y., Sekine, H., Isogaya, M., Ito, S., Ohga, A.: Atropine- and hexamethonium-resistant motor response to greater splanchnic nerve stimulation in the dog stomach. J. Auton. Nerv. Syst., 1987; 20: 35-42.
Bueno, L., Praddaude, F.: Electrical activity of the gallbladder and biliary tract in sheep and its relationships with antral and duodenal motility. Ann. Biol. Anim. Bioch. Biophys., 1979; 19: 1109-1121.
Bueno, L., Ruckebusch, Y.: Effect of anticholinergic drugs on the electrical activity of the antrum and duodeno-jejunum in sheep. J. Vet. Pharmacol. Ther., 1978; 1: 225-232.
Eglen, R.M., Hedge, S.S., Watson, N.: Muscarinic receptor subtypes and smooth muscle function. Pharmacol. Rev., 1996; 48: 531-565.
Caulfield, M.P., Birdsall, J.M.: International union of pharmacology. XVII. Classification of muscarinic acetylcholine receptors. Pharmacol. Rev., 1998; 50: 279-290.
Ogishima, M., Kaibara, M., Ueki, S., Kurimoto, T., Taniyama, K.: Z-338 facilitates acetylcholine release from enteric neurons due to blockade of muscarinic autoreceptors in guinea pig stomach. J. Pharmacol. Exp. Ther., 2000; 294: 33-37.
Dobrilla, G., de Pretis, G., Comberlato, M., Amplatz, S.: Pirenzepine and upper gastrointestinal tract motility in man. Hepato-gastroenterology, 1988; 35: 51-53 (review).
Schiavone, A., Sagrada, A., Pagani, F., Giachetti, A.: Role of muscarinic receptor subtypes in the regulation of migrating myoelectric complex in the dog. Gastroenterology, 1989; 96: 116-121.