POTASSIUM NET EFFLUX IN RELATION TO WATER MOVEMENT ACROSS THE MEMBRANE OF FROG SARTORIUS MUSCLE FIBERS

摘要

It is the main purpose of this report to elucidate the movement of K ions (particularly net efflux) in connection with water movement. 1. When water moved osmotically across the plasma membrane, K net efflux, independent of water movement, could be observed. 2. When the muscle was transferred from distilled water or sucrose to K free Ringer, the transient increase in K net efflux in K free Ringer was observed and was two or three times the K efflux which was increased in distilled water. The transient increase in K efflux had no close relation with total [K]i. The [K]i was not the primary cause for K net efflux. The total [K]i obtained with flame-photometer did not immediately signify the driving force for K net efflux. 3. The shorter the time of interrupting immersion with Ringer in moving from distilled water, sucrose, or K free Ringer to K free Ringer, the larger was the rate of increase in K efflux during the following soaking with K free Ringer. The transient increase in K efflux became less with approaching to the balanced state of K ions in Ringer; in other words, high [K]i, on the contrary, tended to inhibit the K net efflux. 4. The increase in K efflux from a transversely cut section of the muscle did not result from higher [K]i and was not the immediate cause for the decrease in [K]i. 5. Considering from the viewpoint of homeostasis, K net efflux described here may be a subordinate molecular phenomena at the membrane.