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KMID : 0377519820070040281
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Chung-Ang Journal of Medicine
1982 Volume.7 No. 4 p.281 ~ p.290
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Intracellular Calcium ion Activities at Resting and Contractured States of Rabbit Papillary Muscles Measured by Calcium-Selective Electrode
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Cho Sung-Il
Uhm Dae-Yong
Rhee Sang-Don
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Abstract
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The intracellular calcium ion activities were measured in the isolated papillary muscle empolying the microelectrode which was made selectively sensitive to Ca^++ by filling with ETH-1001, calcium selective neutral carrier. Changes of intracellular calcium ion activities in resting state superfused with normal Tyrode solution and during the development of centracture induced by superfusion with sodium-free Tyrode were investigated. REsults were summarized as follows; 1. Selectivity characteristics of Ca^++ selective electrodes to calcium were maintained for considerably longer period when 14wt.% PVC was added to ETH-1001 solution than ETH-1001 alone. 2. When calcium-selective electrode was inserted to miscle tissues at the resting period, mean value of intracellular calcium ion activity was pCa 7.1. This corresponds to 247 nM in terms of concentration,assuming the activity coefficient of intracellular calcium ion was same as that of extracellular Ca^++. 3. During superfusion with sodium-free Tyrode, the initial change of resting membrane potential was hyperpolarization which was returned to normal values before contracture was fully developed. In the initial periods, amplitides of twitch increased and the duration of action potertials was shortened. these changes are in agreement with those which are seen when the intracellular calcium selevated. 4. Contracture was induced by superfusing with, sodium-free Throde for 30∼60 min, and resting tension was restored to the control level, the muscle responded to stimulation. 5. The intracellular calcium ion activities were around pCa 4.7. in contractured state which corresponded to 104∼205% of control twitch tension. In terms of caclium ion activity, it was about 250 times greater than of resting state.
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