Effects of oral administration of trimebutine on colonic propulsion in conscious mice were studied by measuring the time required to evacuate a bead which had been inserted into the colon, and compared with those of metoclopramide and domperidone. In normal animals, trimebutine (10 and 50 mg/kg), metoclopramide (50 mg/kg) and domperidone (50 mg/kg) had no effect on the bead evacuation. Metoclopramide and domperidone at 30 mg/ kg showed no effect on the delay of colonic propulsion induced by clonidine, while trimebutine (10 and 30 mg/kg) restored the delay significantly. Trimebutine also showed restoration of the delay induced by loperamide. On the acceleration of the propulsion induced by neostigmine, trimebutine (10 and 30 mg/kg) showed an inhibition. In addition, trimebutine (3-30 mg/kg) dose-dependently suppressed the development of soft feces and/ or diarrhea induced by neostigmine. According to the results, it is concluded that trimebutine produces both acceleration and inhibition on the colonic propulsion in mice.

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While the micturition reflex was induced in dog by infusion of Ringer solution into the bladder, the following four types of electrical activity were picked up by two bipolar wire electrodes, embedded in the posterior wall of bladder and in the prostatic part of male urethra; ‘intravesical ureter potential’ and ‘detrusor spike’ by bladder electrode, and‘slow wave’ and ‘external sphincter spike’ by urethral electrode. The relative size, respective rhythm and timing of discharge during voiding cycle were specific for each of them and they were readily identifiable for their own sources.
The ‘ureter potential’ was not actively related to the voiding cycle but its triphasic wave form was dissociated at the maximum contraction phase of the bladder. Unexpected finding was the ‘quasi-synchronization’ of discharges between detrusor and external sphincter. The entire discharges in both muscles were consisted of ‘initial burst’, ‘intermittent inhibition’ and ‘prolonged after-discharge’. The initial burst of detrusor was definitely delayed in comparison with that of external sphincter, but the end of prolonged after-discharges was again synchronized in both muscles. The possible mechanism for synchronization was discussed.
The ‘slow wave’ was sometimes superposed on the tonic discharge of external sphincter recorded by same wire-electrode in urethral wall, therefore, their properties were analyzed under the condition of‘immobilization’ of external sphincter. The sustained waxing and waning ‘slow waves’, observed in all female urethrae and one-fifth of male urethrae, were markedly suppressed by elicitation of isovolumetric rhythmic contractions of bladder with fall of intraurethral pressure. This bladder-dependent behavior of‘slow wave’ was interpreted as a sign of‘urinary’ sphincteric activity of urethral circular muscle. On the other hand, ‘spontaneous’ cyclic activation of ‘slow wave’ which was seen in about four-fifth of male urethrae and was not dependent upon the state of bladder, was interpreted as a sign of ‘genital’ sphincteric activity of the same circular smooth muscle.

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Isolated gallbladders of both hamsters and mice showed a contractile response consisting of initial and secondary contractile responses to electrical stimulation with rectangular pulses (50 volt, 40 Hz) of 6 msec duration for a period of 10 seconds. The duration time of the contractile response was very long.This was because the duration time of the process of the initial contractile response was as short as 5 to 40 seconds, but that of the secondary contractile response was as long as 8 to 15 minutes. Both initial and secondary contractile responses of the gallbladder in both hamsters and mice were little affected by atropine (1×10^-6M), guanethidine (1×10^-6M) and tetrodotoxin (1×10^-7M). In both animals, further, the initial contractile response of the gallbladder was little affected by indomethacin (1×10^-5M) and 5, 8, 11, 14-eicosatetraynoic acid (ETYA) (5×10^-6g/ml), while the amplitude of the secondary contractile response of the gallbladder was significantly reduced by such drugs. From these results, we obtainthe following conclusions: 1) In both animals, the intramural nerves of the gallbladder may have no influence on the both initial and secondary contractile responses of the gallbladder. 2) The initial contractile response is probably mediated by a direct effect of the electrical stimulation to the muscle in the wall of the gallbladder, while the secondary contractile response is probably attributable to prostaglandins released from the wall of the gallbladder by a direct effect of the electrical stimulation to the wall.

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