Effect of removal of external calcium on phosphoinositide hydrolysis in cultured myotubes of embryonic chicken.
The effect of removal of external Ca2+ 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 Ca2+, the hydrolysis of phosphoinositide was significantly increased by exposure to 80 mmol/L K+ solution. After removal of external Ca2+, 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 Ca2+ is essential for this effect, which is different from mature muscle fibres.
Wu
D
D
Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai 200031.
Zhang
X H
XH
Zhu
P H
PH
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D002642:Chick Embryo; D004075:Diglycerides / Q000378:metabolism; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*
D004075:Diglycerides; D010716:Phosphatidylinositols; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium