The Third Department of Internal Medicine, Tohoku University School of Medicine
Department of Applied Physiology, Tohoku University School of Medicine
Department of Physiology, Tohoku University School of Medicine
1988 Volume 156 Issue 1 Pages 13-21
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The mechanical properties of the longitudinally cut preparations of the guinea-pig hepatic duct were studied. About 42% of the preparations (18 of 43 preparations) showed spontaneous phasic contractions which were unaffected by either tetrodotoxin, guanethidine or atropine. About 60% of them exhibited phasic contractions which appeared at irregular frequencies in the same tissue and varied in size. This sort of contractions usually accompanied small contractions. In about 20%, contractions occurred constantly in frequency (about 6-14 every 10 min) and in size. The remaining 20% showed twitch-like contractions which occurred sporadically. These contractions were classified into two types depending upon the susceptibility to the Ca2+ entry blocker, D-600. D-600 (1-100μM) strongly suppressed both regularly occurring contractions and twitch-like ones. On the other hand, the drug was ineffective on irregularly occurring contractions. The Ca2+ sources underlying these contractions were discussed.