Anaerobic Uptake of Potassium by Frog Muscle

Abstract

Steinbach 1 has shown that frog muscle loses potassium in exchange for sodium when the muscle is soaked in potassium-free Ringer's solution. He also showed that when potassium depleted muscles are placed in Ringer's solution containing potassium, they regain potassium at the expense of sodium. This uptake of potassium in exchange for sodium requires work which must be supplied by the muscle. It has previously been shown that muscle retains its potassium in Ringer's solution in the absence of oxygen. 2 The present investigation was undertaken to determine the influence of aerobic respiration on the uptake of potassium under the conditions of Steinbach's experiments.

The sartorius, semitendinosus, and tibialis anticus longus muscles from recently caught frogs were dissected and placed in potassium-free Ringer's solution containing M/3000 phosphate buffer, pH 7.4. After one hour the muscles from one frog were transferred to 250 ml of K-free Ringer's solution which was stirred by a current of air and kept in a cold room at 4CC. After about 17 hours the muscles were divided into sets for further treatment. This treatment was of 3 sorts, (a) immediate analysis, (b) analysis after immersion for 4 or 7∗/2 hours in 25 ml of Ringer's solution containing 10 mM K and M/150 phosphate buffer and continuously equilibrated with air, (c) the same as (b) but continuously equilibrated with pure nitrogen starting 1/2 hour before the muscles were introduced. Paired sets of muscles were used to compare treatments (a) and (b), (b) and (c), and (a) and (c), as shown in Table I. Fenn and Cobb 3 state that muscles lose more potassium in Ringer's solution containing m/3000 phosphate than in M/150 phosphate. One incomplete experiment showed no difference in the uptake of potassium from solutions containing M/3000 and M/150 phosphate buffer.