Effect of temperature on the contractile response of isolated rat small intestine to acetylcholine and KCl: calcium dependence.
The influence of temperature on phasic and tonic components of isometric tension of the isolated rat small intestine was investigated at two temperatures (15 degrees C and 21 degrees C) where spontaneous movements were not evident. Warming did not shift acetylcholine-response curve whereas it enhanced the amplitude of maximal tension. The rate of tension development varied with acetylcholine concentration and increased with temperature. Warming enhanced and accelerated responses to single doses of high KCl. The effect of temperature on acetylcholine responses was mimicked by lowering calcium concentration in the bathing medium but in zero-calcium medium responses were higher at 21 degrees C than at 33 degrees C. Discussion of previous reports underlines that opposite observations on the effect of temperature on smooth muscle contraction are mainly explained by experimental protocols. In turn, it is suggested that the obtained effects of temperature might be related to the regulation of intracellular calcium concentration.
Sabeur
G
G
Laboratoire de Physiologie, Faculté de Médecine, Marseille, France.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D003080:Cold Temperature; D003470:Culture Media; D004347:Drug Interactions; D005260:Female; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000187:drug effects; D007537:Isometric Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D003470:Culture Media; D011189:Potassium Chloride; D000109:Acetylcholine; D002118:Calcium