THE CORRELATION BETWEEN ENHANCED AFTER POTENTIAL BY LESS PERMEABLE ANIONS AND CA IONS

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  • 低透過性陰イオンによって増大した骨格筋活動電位の後電位とCaイオンとの関係
  • テイ トウカセイ インイオン ニ ヨッテ ゾウダイシタ コッカクキン カツドウ

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Abstract

The correlation between negative after potential of striated muscle and Ca ions as a trigger of excitation contraction coupling had been investigated on the enhanced negative after potential by substitution of Cl ions with less permeable nitrate ions.<BR>The monophasic action potential was obtained by cutting the one end of sartorius muscle of Rana pipiens.<BR>Replacement of Ringer's choloride by nitrate ions (NO3-Ringer) results in the prolongation and augmentation of negative after potential. The duration of negative after potential in NO3-Ringer became minimum when Ca concentration was twice of normal, and was augmented by both decreasing and increasing Ca ions. It reached about 120% of original value when Ca concentration was 10 times of normal or free.<BR>The positive after potential appeared following the augmented negative after potential in NO3-Ringer, and was also influenced by Ca ions. The amplitude of positive after potential was minimum when Ca content was half of normal and was augmented by both increasing and decreasing Ca concentration. It reached about 180% of original value when Ca concentrations were 10 times of normal or free.<BR>Both negative and positive after potentials in NO3-Ringer as well as negative after potential in Cl-Ringer disappeared in the glycerol treated preparation.<BR>From these results it was supposed that the after potential of muscle was intensively associated with the action of T-system and that some part of this potential might be initiated by Ca influx in T-system which has different excitable property from muscle membrane.

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