[Potassium ion transport in the erythrocytes of the frog Rana ridibunda].

The K+ transport in isolated erythrocytes from the frog Rana ridibunda has been studied using 86Rb as a tracer at the temperature of 18-20 degrees C. At physiological K+ concentration (3 mM) in C1- medium ouabain and furosemide inhibited K+ influx by approximately 42 and 47%, respectively. Furosemide had no effect on the Na+ (22Na) transport under the same conditions. The replacement of C1- by NO-3 in medium resulted in significant decrease of total K+ influx, which was not inhibited by furosemide. The ouabain- and furosemide-sensitive components of K+ influx hyperbolically increased as a function of external K+e concentration (1-90 mM) in C1- medium and calculated values of Vmax were 2.2 +/- 0.14 and 5.8 +/- 1.2 mmol/1 cells/h, respectively. K+ influx into frog erythrocytes in the presence of both ouabain and furosemide in NO-3 medium was significantly lower compared with C1- medium. C1--dependent, furosemide-insensitive component of K+ influx increased in a saturable fashion in the range of K+e concentration from 1 to 90 mM. Residual component of K+ transport in NO3 medium in the presence of the blockers was a linear function of K+e concentration and is characterized by the constant of K+ influx rate equal to 0.028 +/- 0.002 h-1. The data obtained indicate that in parallel with the Na, K-pump specific K, C1-transporter participates in K+-transport in the frog erythrocyte membrane. The latter mechanism was only partially blocked by 1 mM furosemide.