Summary
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1.
The effects of bethanechol and morphine on electrical and motor activity of the colon were studied by means of needle electrodes and extraluminal strain transducers in 6 unanesthetized cats.
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2.
Bethanechol and morphine stimulated circular contractions to a similar extent. The contractile pattern after bethanechol injection appeared to be more organized than that after morphine. Bethanechol often caused defecation, morphine induced vomiting.
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Both drugs lowered slow-wave frequency and increased the occurrence of faster electrical potentials. But bethanechol predominantly activated spiking, whereas the opiate caused long sequences of oscillations besides enhancing spike activity.
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It is concluded that electromyography of the colon in situ allows differentiation between the effects of the two drugs and indicates different mechanisms of action. The apparent differences observed during previous experimentsin vitro with regard to slow-wave frequency point to the influence of extracolonic factors on the colonic slow wave.
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This work was submitted as part of a thesis in partial fulfillment of the requirements for the habilitation, University of Marburg.
The work was supported in part by “Professor Dr. Adolf Schmidtmann-Stiftung” and by Deutsche Forschungsgemeinschaft Wi 285/2.
I am greatly indebted to Dr. J. Christensen, Department of Internal Medicine, University of Iowa, for his invaluable support and his numerous helpful suggestions and to Dr. N. W. Weisbrodt, University of Texas Medical School in Houston, for his help and his advice.
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Wienbeck, M. The electrical activity of the cat colonin vivo . Res. Exp. Med. 158, 280–287 (1972). https://doi.org/10.1007/BF01852211
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DOI: https://doi.org/10.1007/BF01852211