By the extracellular recording technique, the action potentials and spontaneous contractions of the isolated rat longitudinal portal vein strips were simultaneously recorded in the presence of varying concentrations of electrolytes, various vasoactive agnets, and hormones, and the mechanisms regulating the force and frequency of spontaneous contraction of the vascular smooth muscle were investigated.
A longitudinal stretch (-200% of the initial length), a higher [K⁺] ₀ (-30mM), a lower [Na⁺] ₀, epinephrine, acetylcholine or ouabain increased both force and frequency of the phasic contractions. A lower [Na⁺] ₀ or ouabain raised basal tone of the muscle in addition to the above effects. A higher [Ca⁺⁺] ₀ increased the contractile force, while it decreased the frequency. A lower [Ca⁺⁺] ₀, calcium channel blocker or VIP reduced the contractile force but increased the contractile frequency. A bigger force and a higher frequency of the phasic contractions were exhibited in the portal vein strips isolated from rats with CCl₄-induced experimental portal vein hypertension. They were similar to responses of the strips from the intact rats to stretch, ouabain, or higher [Ca⁺⁺] ₀ in the presence of lower [Na⁺] ₀.
These results suggest that an initiation and force of the phasic and tonic contractions depend on extracellular Ca⁺⁺ concentration and influx of Ca⁺⁺, and frequency of the phasic contractions, mainly on membrane potential rather than on extracellular Ca⁺⁺ concentration. In the portal hypertension, permeability of the cell membrane to Ca⁺⁺ is possibly increased.

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The 24-hr gastric and duodenal pressure measurement was performed in 5 patients with non-ulcer dyspepsia (NUD). The reduction of incidence of IMC and prolongation of the first appearance of IMC after evening meal were observed in NUD patients. The gastroprokinetic agent, cisapride 5mg, 3 times a day for 7 days significantly increased the incidence of IMC and shortened the time before the first appearance of IMC after evening meal. This result indicates that in NUDpatients impaired gastrointestinal motility is present in fasting phases and cisapride may be useful for correcting motility disorders.

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Interdigestive contractile activity of the gastric body, antrum, pyloric ring andduodenum was recorded by means of chronically implanted force transducers in 5 conscious dogs. In accordance with interdigestive phase III contractions in the gastroduodenal region, a burst of strong contractions and remarkable relaxations were observed to occur in the pyloric ring. In accordance with the intense phase III contractions in the antrum, the pyloric ring was relaxed and duodenal contractions declined and ceased as if the passage of gastric contens expelled by the strong contractions in the antrum were being done smoothly. With the termination of the antral contractions, it was observed that the duodenal contractions were initiated and followed immediately by tonal increase in the pyloric ring superimposed with phasic contractions. These coordinated contractions between the pyloric ring and the duodenum appear to prevent reflux of duodenal contens to the stomach.
Bilateral vagal cooling blockade abolished this coordination. As the gastric contractions ceased completely during vagal cooling blockade, irregular phasic contractions were initiated and no relaxation was observed on the pylorus.
In conclusion, the pyloric ring is a true functional sphincter which regulates gastric emptying and prevents reflux from theduodenum in the interdigestive state, and these coordinated contractions are regulated by the vagal nerves.

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The adrenergic alpha-1 and -2 adrenoceptors inhuman hypertrophied and non-hypertrophied prostatic adenomas were measured in the saturation experiment using 3H-prazosin and 3H-yohimbine. Not only alpha-1adrenoceptor but also alpha-2 adrenoceptor were found to exist with great amount in prostatic adenomas. In the inhibition experiment selective alpha-1 antagonists, prazosin and terazosin inhibited the 3H-prazosin or 3Hyohimbine bindings to prostatic adenomas. The ability as alpha-1 antagonist is ten times greater in prazosin than in terazosin, but that as alpha-2 antagonist is greater in terazosin than in prazosin. These data suggest that terazosin may have other effects than the relaxation of prostatic smooth muscles in hypertrophied prostatic adenoma.

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