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KMID : 0377519870120030347
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Chung-Ang Journal of Medicine
1987 Volume.12 No. 3 p.347 ~ p.360
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Effects of Diltiazem on the Staircase Phenomenon in Rabbit Papillary Muscles
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Abstract
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Effects of diltiazem on staircase phenomenon were investigated in rabbit papillary muscles partially depolarized by 19 mM K-Tyrode solution.
The following results were obtained:
1. Contractile forces were increased in parallel with the increase of stimulation frequencies from 0. 2 Hz
to 2 Hz in the muscle preparation partially depolarized around -50 mV by 19 mM K-Tyrode solution.
2. Contractile forces induced by various frequencies of electrical stimulation were markedly changed
in high Ca 21 solution, while those were not remarkable in low Ca-+ solution.
3. The relationship between developed tension and stimulation frequency were negatively inverted in low concentration of diltiazem(0. 05 and 0. 1 ma/1).
4. Amplitudes of action potentials were reduced in administration of low calcium and diltiazem which affected calcium flux during action potential.
5. Durations of action potential were prolonged in lotw calcium solution and those were shortened in low concentration of diltiazem.
6. Amplitudes of action potential in diltiazem-treated 19 mM K-Tyrode solution were continuously r e-Wced by change in stimulation frequencies from low to high rate.
_´tibo.re results suggests that amplitudes of action potential closely related with contractility of rabbit papillary muscle in 19 mM K-Tyrode solution and decreased influx of calcium during action potential could be related with negatives staircase phenomenon.
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