Nov 1, 1976

Changes in extracellular potassium activity in response to decreased pH in rabbit atrial muscle

Circulation Research
R B Skinner, D L Kunze


The extracellular and intracellular potassium (K+) activities of isolated superfused rabbit atrial muscle were measured using K+-sensitive liquid ion exchanger microelectrodes. When the pH of the bathing medium was decreased from 7.5 to 6.8, intracellular K+ activity fell and extracellular K+ activity rose from a mean control level of 3.6 mM to a new steady state level of 3.9 mM after 1 hour. When the pH was further decreased to 6.1, extracellular K+ activity increased to a mean of 4.9 mM. Following the change in pH, the increase in extracellular K+ activity occurred over a period of 30-40 minutes at which time a stable value was reached and maintained for the next hour. On return to normal pH the extracellular K+ activity returned to control with a time constant of 20 minutes or less. Measurements of intracellular K+ activity over 1 hour showed a mean loss of 3 mM at pH 6.8 and a mean loss of 8 mM at pH 6.1. The loss was reversible within 20 minutes of return to control pH. The increase in extracellular K+ activity was accompanied by a decrease in resting membrane potential as well as decreases in maximum dv/dt and overshoot of the action potential. The action potential contour underwent complex changes consisting of decrease ...Continue Reading

Mentioned in this Paper

Resting Potentials
Extracellular Space
Action Potentials
Right Atrial Structure
Culture Techniques

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