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Effect of removal of external calcium on phosphoinositide hydrolysis in cultured myotubes of embryonic chicken

Wu Di, Zhang Xiaohui, Zhu Peihong

Shanghai Institute of Physiology,Chinese Academy of Sciences.Shanghai 200031

Abstract

The effect of removal of external Ca~(2+) on phosphoinositide hydrolysis was investigated in cultured myotubes from 9-day-old Leghorn embryonic chicken. In the myotubes exposed to Ca~(2+)-free Ringer^s solution, the turnover of phosphoinositide was exponentially decreased with a time constant of about 26 min. In the presence of external Ca~(2+), the hydrolysis of phosphoinositide was significantly increased by exposure to 80 mmol/L K~(+) solution. After removal of external Ca~(2+), 80 mmol/L K~(+) exposure caused a slight decrease of phosphoinositides hydrolysis in comparison with the control (normal Ringer). It is indicated that hydrolysis of phosphoinositide in cultured myotubes can be enhanced by high K~(+) exposure. External Ca~(2+) is essential for this effect, which is different from mature muscle fibres.

Key words: High K~(+);Ca~(2+)-free;Phosphoinositide;Myotube

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Citing This Article：

Wu Di, Zhang Xiaohui, Zhu Peihong. Effect of removal of external calcium on phosphoinositide hydrolysis in cultured myotubes of embryonic chicken. Acta Physiol Sin 1999; 51 (4): (in Chinese with English abstract).