Temporal Relationship between Action Potential and Ca^ Transient in Characean Cells

元データ 日本植物生理学会


Temporal relationship between the action potential and the change in cytosolic Ca^<2+> concentration was investigated in cells of four species of Characeae, Chara corallina, Nitellopsis obtusa, Nitella flexilis and Nitella axilliformis. The Ca^<2+> transient was detected by light emission from Ca^<2+>-sensitive photoprotein aequorin injected into the cytoplasm. Action potential was triggered by an outward or sometimes inward electric current pulse of 20-50 ms in most cases. In all species the action potential started at almost the same time as the time at which the light emission from aequorin began to increase. Also the peak of action potential almost coincided with that of light emission, which is in contrast with the slower Ca^<2+> transient in Chara reported by Thiel et al.[(1997)J.Exp.Bot.48: 609]. A discussion was made on the orgin of Ca^<2+> transient and the ionic processes during membrane excitation.


Tazawa Masashi Department Of Applied Physics And Chemistry Fukui University Of Technology
Kikuyama Munehiro Biological Laboratory The University Of The Air.
Kikuyama Munehiro Biological Laboratory The University Of The Air
Tazawa Masashi Departlnent Of Biology Faculty Of Science Osaka University