|
KMID : 0377519770020010019
|
|
Chung-Ang Journal of Medicine
1977 Volume.2 No. 1 p.19 ~ p.26
|
|
|
Influence of Decreased Na^+ and Cl^- Concentration on Frog Atrial Muscle Action Potential and Contractillity
|
|
Kim Man-Jae
Uhm Dae-Yong
Rhee Sang-Don
|
|
|
Abstract
|
|
|
|
To investigate the effects of decreased extracellular Na and Ci ion concentration on atrial muscle of frog, changing patterns of single cell action potential by means of glass ultramicroelectrode and tension curves of isometric contraction in atrial muscle strips were recorded simultaneously. The results were as follows: 1. Decreased Na^+ and Cl^- concentration had little effects on resting transmembrane potential but amplitude of action potential and size of the overshoot were decreased along with the decrease of the concentration. The peak of the action potential had not reached "O" potential difference after 25 minutes bathing 1/2, 1/4 of the normal Na^+ and Cl^- concentration. 2. -dV/dt in plateau phase were tended to increase according to the decrease of Na^+ and Cl^- concentration and significantly increased in less than 1/4 of the normal concentration. -dV/dt in repolarization phase were scarcely affected to Na^+ & Cl^-. 3. Duration of action potential were significantly decreased in low concentration such as 1/2 of the normal Na^+ and Cl^- concentration. 4. Atrial muscle contractility were increased in decreased Na^+ & Cl^- concentration but the degree of increment were relatively decreased with time. 5. Frequency of the contraction were dominantly affected by decreased Na^+ & Cl^- than any other parameters and decreased. Above results were considered as that Na^+ played a important role in maintaining upstroke phase and slow inward current of plateau phase in atrial muscle action potential and Na^+ also had influence on the flux of Ca^++ across the membrane or the control of available intracellular Ca^++ concentration.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|