Abstract
Effect of the K+ concentration of outer medium on the injury potential in the ureter (Cabia cobaya) was measured and the results were compared with that of the sartorius muscle (Bufo vulgaris) . It is well known fact, that the injury potential of smooth muscles decays rapidly. Therefore the measurement was performed skillfully within 30 second after making the cut at the end of the ureter. Before each measurements, new cut was made on the ureter. In higher concentration of K+, the potential decreased proportionally to the log [K+] of the outer medium. Postulation of Nernst's theory was favored for the both results in the sartorius and in the ureter.
But in the lower concentration of K+, the experimental results deviated from the theoretical. The potential indicated always lower value than the postulation of Nernst's formula. Such deviations are, according to Hodgkin's idea, owe to the existence of active transport of the K+ in the muscle cell. The deviation occures at [K+] =0.7m M/1 in the sartorius muscle, and [K+] =0.25m M/1 in the ureter. From these results, it can be supposed that the intensity of active transport is stranger in the sartorius muscle than in the ureter muscle.
