Propulsive activity in segments of isolated distal colon of guinea-pig was investigated. Propulsive activity, as indicated by movements of the bolus (5×10 mm diameter) made of plastic with a steel wire, was recorded isometrically using a force-displacement transducer. Muscle tension of longitudinal axis was also recorded isometrically in the same preparation.
In all preparations, spontaneous propulsive activity, which was due to combination of ascending excitation and descending inhibition, occured periodically.
The frequency of propulsive activity was 4.0±0.9/10 min (M±SE, n=8) and the duration was 64.0±9.0 sec (M±SE, n=9). The propulsive force was 16.4±3.4 g (M±SE, n=10) at peak.
The spontaneous propulsive activities were blocked by atropine (10^-5 g/ml). These activities were gradually decreased in frequency and in propulsive force within 2-3 hours.
When spontaneous propulsive activities were negligible, carbachol (10^-9-10^-7 g/ml) added to the bathing medium stimulated propulsive activity in a dose dependent manner.

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Effects of trimebutine maleate (TM-906) on the spontaneous motility of the gastrointestinal tracts were investigated in anesthetized dogs by means of force transducers. TM-906, administrated intravenously or intraduodenally, produced an inhibition followed by a potentiation of the spontaneous motility in the stomach, and caused a potentiation of the spontaneous motility in the duodenum, jejunum, ileum and colon. These effects of TM-906 were observed also in the vagotomized dogs as in the intact dogs. From these results, it is suggested that TM-906 modulates the spontane-ous motility of the gastrointestinal tracts primarily through the peripheral mechanism.

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The Role of the striated urethral sphincter on the dynamics of micturition was studied using 4 decerebrated dogs. The voiding cycles were analyzed by pressure flow EMG and pressure flow plot studies before and after the administration of suxamethonium. In the control condition, highly reproducible reflex micturition with bladder contraction and spasmodic rhythmic sphincter contractions was demonstrated. After the administration of suxamethonium reflex micturition occurred, but there was decreased bladder emptying as well as absence of spasmodic rhythmic sphincter contractions. The striated urethral sphincter would seem to play an important role in bladder emptying of decerebrated dogs.

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The effects of trimebutine (2-dimethylamino-2-phenylbutyl-3, 4, 5-trimethoxy benzoate hydrogen maleate) and metoclopramide (N-diethylaminoethyl-2-methoxy-4-amino-5-chlorobenzamide) on propulsive activity of the isolated segmental colon, and on longitudinal and circular muscle layers of colon in guinea-pig were investigated.
Trimebutine in doses up to 10^-7g/ml slightly stimulated propulsive activity, but in doses as high as 10^-7g/ml inhibited it. However, metoclopramide (10^-7-10^-5g/ml) stimulated propulsive activity in a dose dependent manner. Neostigmine-stimulated propulsive activity was inhibited by trimebutine (10-6g/m/) but potentiated by metoclopramide (10^-5g/ml).
Trimebutine (10^-8-10^-5g/ml) contracted circular muscle layer in a dose depen-dent manner, and contracted longitudinal muscle layre in doses up to 10^-7g/ml, but in doses as high as 10^-7g/ml relaxed it. While, metoclopramide (10^-8-10^-5g/ml) contracted both muscle layers.
These results indicate that, at high doses, trimebutine-induced inhibition of propulsive activity may depend on a relaxation of longitudinal muscle, and at low doses, trimebutine-induced stimulation of propulsive activity may depend on a contraction of longitudinal muscle which was partly inhibited by atropine (10^-6g/ml), though metoclopramide at low doses had little effect on propulsive activity.

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