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KMID : 0377519830080020159
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Chung-Ang Journal of Medicine
1983 Volume.8 No. 2 p.159 ~ p.166
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Effects of Propranolol on the Ca^++ -Regulation of Cardiac Sarcoplasmic Reticulum
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Song Young-Myung
Shin Sang-Goo
Lee Kwang-Soo
Kim Hae-Won
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Abstract
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Propranolol is one of clinically useful antiarrhythmic agents and classified as group Ⅱ in its electrophysiological aspect. The negative inotropic effect which is unrelated to its β-adrenolytic action has been demonstrated with high concentration of propranolol. It has been well known that the calcium plays a central role in excitation-contraction coupling process of myocardium and also in electrophysiological changes of cell membrane. To investigate the possible mechanism of myocardial depressive action of propranolol, the study was made on effects of propranolol on calcium uptake and ATPase activity of fragmented sarcoplasmic reticulum. 1. The maximum Ca^++ -uptake of sarcoplasmic reticulum is inhibited by propranolol in a dose dependent manner. 2. The release of calcium from sarcoplasmic reticulum is not affected by propranolol, but which higher than 1×10^-3M of propranolol, the rate of calcium release from sarcoplasmic reticulum is decreased. 3. Both Ca^++ -and Mg^++ -ATPase activities of sarcoplasmic reticulum are inhibited dose-dependently by propranolol. It is suggested from the above findings that the cardio-depressive effect of propranolol may be partially explained by the inhibition of Ca^++ -regulation of sarcoplasmic reticulum which may result in the decrease of available intracellular calcium store in the excitation-contraction coupling process of myocardium.
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