The effect of hypothermia on carbachol-induced contractions of the rabbit isolated detrusor smooth muscle and the role of calcium, potassium and sodium channels in this action

İn this study, the effect of hypothermia on the carbachol-induced contractions and the role of calcium, potassium and sodium channels in this effect were investigated in the rabbit isolated detrusor smooth muscle of urinary blad- der. The contractions induced by 10'6 M carbachol were enhanced by cooling of medium from 37 to 28°C. The hypothermia-induced contractions were not inhibited by 10'6 M verapamil and tetraethylammonium (TEA, 10'4 M) the blocker of Ca2 + -activated K* channels but were enhanced in the presence of 3x10'4 M caffeine and reduced by the sodium-channel blocker pilsicainid ( W 7 M) significantly. When these procedures were repeated in the Ca2 + -free Solutions, the carbachol-induced contractions were smaller than that of obtained in normal medium and these responses were enhanced by cooling. These results suggest that, intracellular Ca2 + pools and memb- ranal Na+ channels but not Ca -activated /C channels may play a functional role in the cooling-induced cont­ ractions of rabbit detrusor smooth muscle.