| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1990: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
Although polyamines are organic cations ubiquitously occurring in living tissues including gastrointestinal (GI) smooth muscle, any possible physiological or pharmalogical role of these amines on GI motor function has scarcely been investigated. We conducted preliminary in-vitro and in-vivo experiments to examine the effects spermine, one of the polyamines, on GI smooth muscle contractions.
All in-vitro experiments were performed on longitudinal ileal strips from male Sprague-Dawley rats, which were suspended in a tissue-bath containing a physiological salt solution with 1.25 mM Ca^<2+>. Spontaneous phasic contractions measured isometrically were markedly inhibited by 3_x10^<-4> M spermine. The presence of 6_x10^<-6> M tetrodotoxine or 1_x10^<-5> M propranorol exhibited no effect on the inhibitory effect of spermine. The inhibitory effect, however, was counteracted by raising the calcium concentration from 1.25 to 3.5 mM.
In conscious dogs, contractile activity was recorded from strain g
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auge force transducers and the effects of spermine on GI motility was tested at a intravenous dosage of 30-60 umo1/kg/hr. During the digestive period, a dose of 30 umo1/kg/hr exerted a minimal inhibitory effect on the contractility of the stomach and duodenum, while a strong contraction that mimicked the interdigestive phase III activity occurred in the upper jejunum, which propagated aborally. Spermine 60 umo1/kg/hr produced a marked suppression of the gastric and duodenal motor activity followed by repeated vomiting. Before the emesis, a phase III-like contraction had already appeared at the jejunum, propagating to the ileum. The vomiting ceased with suspension of the spermine infusion, when the entire GI tract took a transient but definite interdigestive pattern. When spermine was administered during the interdigestive period, it evoked repeated emesis but the recycling pattern of migrating motor complex was not essentially disturbed.
Spermine might be involved in the controlling mechanism of the GI motor function and in the mechanism of emesis. Less
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