| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1990: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Ileal longitudinal muscle developed a tension after a lag of approx. 15 min in response to 1 mM iodoaceric acid (IAA) when the tissue ATP concentration falled below 60 - 55 % of the control. As the IAA concentrations is increased, the ATP concentration decreased rapidly, and both the time of the onset and the duraion of the contraction became to shorten. The contraction to IAA also developed in the presence of Ca^<2+> antagonist, D-600, however, the onset time was prolonged. Intracellular Ca^<2+> was enhanced at the onset of the IAA-induced contraction, suggesting that Ca^<2+> acts as a trigger in the formation of rigor linkage in contractile proteins at the onset of ileal rigor.
The contraction to dinitrofluorobenzene (DFB) in ileum consisted of two components; an initial fast contraction which was sensitive to D-600, and a late contraction referred to as a rigor which was resistant to it and followed with decrease in the tissue ATP.
Mn^<2+> (5 mM) inhibited completely the K^+ (60 mM)-induced ileal tonic tension to the base line, however, the tension was progressively increased to the above level of original K^+ tonic response after 3 hr in the presence of the Mn^<2+>. But, at this time, the^<45>Ca uptake determined by lanthanum method remained unchanged from control levels. D-600 inhibited the tension development and Mn uptake in the presence of 5 mM Mn^<2+> in the high-K^+ medium. These results suggeste that Mn^<2+> are slowly accumulated in the intracellular compartsments through voltage operated Ca^<2+> channels and may activate contractile proteins. Further investigations need whether the ileal tension in the presence of Mn^<2+> in high-K^+ medium is a rigor, or not.
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