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EFFECT OF CAFFEINE AND THEOPHYLLINE ON Ca~(2+) SENSITIVITY OF TROPONIN AND Ca ~(2+) RELEASEFROM SR IN SAPONIN-SKINNED RAT CARDIAC MUSCLE

HUANG YAN, HE ZHEN-HE, LI YUN-XIA

(Laboratory of Cardiovacular Physiology, Human Medical University, Changslta 910078)

Abstract

Cell membrane of cardiac muscle fiber (rat right ventricular papillary muscle) was chemically skinned(permeability of membrane increased)by treatment with saponin at low concentration (50 pg/ml)，while the function of sarcoplasmic reticulum (SR) was preserved. The strength of rigor contraction of the skinned fiber was used as a semi- quantitative index of the ability of SR to release Ca~(2+).When treated with saponin at high concentration(500 4g/ml)，both sarcolemma and membrane of SR were skinned. Tension一pCa relationship and the Cat一concentration required for producing 5 0%of maximum Ca~(2+)activated tension (pCaso)were respectively taken as qualitative and quantitative index of Cat一sensitivity of troponin (TN).The results showed:
(1)In low saponin skinned fiber，5 and 10 mmol/L caffeine respectively produced
89.2士12. 7 and 142. 5士17 mg (n = 4) rigor contraction，5 mmol/L theophylline did not have this effect.(2)In high saponin skinned fiber 5 mmol/L theophylline，5 and 10 mmol/L caffeine shifted the tension-pCa relationship curve to the left，pCa5o respectively increased by 0. 212，0. 261 and 0. 274 pCa units. These results suggest that caffeine and theophylline increase the Cat~(2+)sensitivity of TN and caffeine can also induce Cat~(2+) release from SR.

Key words: Key words:saponin;;;;;;

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Citing This Article：

HUANG YAN, HE ZHEN-HE, LI YUN-XIA. EFFECT OF CAFFEINE AND THEOPHYLLINE ON Ca~(2+) SENSITIVITY OF TROPONIN AND Ca ~(2+) RELEASEFROM SR IN SAPONIN-SKINNED RAT CARDIAC MUSCLE . Acta Physiol Sin 1997; 49 (2): (in Chinese with English abstract).