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KMID : 0438219790160010195
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Korea University Medical Journal
1979 Volume.16 No. 1 p.195 ~ p.201
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The Effect of Potassium Ion Concentration on the Tension Development of Rat Heart Muscle
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Abstract
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Effects of potassium ion concentrations in Ringer solution were examined on the contraction patterns of the cardiac muscle of rat. The left ventricular muscle strip (10-12mm long and 3-4mm wide) is fixed between a clip attached to the arm of an isometric transducer and the other clip attached to the move able barrel of a metric micrometer. This preparation is then immersed in 400ml of buffer Ringer through which a mixtur a of 95% 02/5% CO, is continuously bubbled, maintained at 37C with surrounding water bath through heat exchange.
In stimulus experiments, there were pulse stimuli at 30V, 10 msec for twitch curve, 30V, 10msec, 10clsec for tetanic contraction.
For the length-tension relationship in normal Ringer solution and K-free solution, muscle strip length was changed from 6mm resting length to 12mm with lmm increments by turning a metric micrometer.
1. A high K-concentration (42mM Kcl) in Ringer solution induced K contrac ture of the heart muscle strip, the twitch and tetanic tension decreased than an normal Ringer solution.
2. In K-free solution, similar K ion replaced with sucrose, the twitch and tetanic tension increased than in normal. Ringer solution.
3. When high K concentration solution was replaced by normal Ringer solution, heart muscle showed a contraction heights of the normal twitch curve and tetanic curve.
4. Optimal tension development of K-free sloution was shifted to more elongated length than in normal Ringer solution.
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