|
|
|
|
|
|
|
||
The Journal of General Physiology, Vol 65, 695-708, Copyright © 1975 by The Rockefeller University Press
ARTICLES |
CO Lee and HA Fozzard
Activities (a) of intracellular K and Na in rabbit ventricular papillary muslces were determined with cation-selectivve glass microelectrodes and concentrations (C) were estimated with flame photometry. The CK and aK of the muscles were 134.9 +/- 3.1 mM (mean value +/- SE) and 82.6 mM, respectively, at 25 degrees C. The corresponding CNa and aNa were 32.7 +/- 2.7 and 5.7, respectively. The apparent intracellular activity coefficients for K (gammaK) and Na (gammaNa) were 0.612 and 0.175, respectively. Similar results were obtained at 35 +/- 1 degree C. gammaK was substantially lower than the activity coefficient (0.745) of extracellular fluid (Tyrode's solution), which might be expected on the basis of a different intracellular ionic strength. gammaNa was much lower than that of extracellular fluid, and suggest that much of the Na was compartmentalized or sequestered. For external K concentrations greater than 5 mM, the resting membrane potentials agreed well with the potential differences calculated from the K activity gradients across the cell membrane as a potassium electrode. These results emphasize that potassium equilibrium potentials in heart muscle should be calculated by activities rather than concentrations.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  B. Yang, R. Desai, and L. K. Kaczmarek Slack and Slick KNa Channels Regulate the Accuracy of Timing of Auditory Neurons J. Neurosci., March 7, 2007; 27(10): 2617 - 2627. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. M. Sejersted and G. Sjogaard Dynamics and Consequences of Potassium Shifts in Skeletal Muscle and Heart During Exercise Physiol Rev, October 1, 2000; 80(4): 1411 - 1481. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. W. Linz and R. Meyer Modulation of L-type calcium current by internal potassium in guinea pig ventricular myocytes Cardiovasc Res, January 1, 1997; 33(1): 110 - 122. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Lee, D. Uhm, and K Dresdner Sodium-calcium exchange in rabbit heart muscle cells: direct measurement of sarcoplasmic Ca2+ activity Science, August 8, 1980; 209(4457): 699 - 701. [Abstract] [PDF]
|
|
|
|
