Some effects of carbon dioxide on intracellular potassium in frog muscle

The short-term effect of carbon dioxide on resting potential (Em), intracellular potassium activity (aiK) and intracellular pH (pHi) has been investigated in frog skeletal muscle. The external pH was kept constant in the range 6.8-7.6 by addition of HCO-3 in presence of CO2. Measurements were done in single or surface fibres of the semitendinosus muscle. CO2 reduced quickly Em and aiK at high but not at low PCO2. This effect persisted in presence of ouabain (10(-5) M). These actions of CO2 are largely accountable for by osmotic swelling, but additional factors are involved.