Potassium outflow in the presence of high concentration of potassium in guinea pig's taenia coli.

In the previous work (1), potassium (K) exchange was studied in the presence of high concentration of K (40 mm K) in guinea pig's taenia coli by measuring the cellular K content and 42K uptake. In the pre sent work, K outflow rate constants were estimated by 42K outflow studies for the purpose of comparing the constants with those obtained in the previous work. A strip of guinea pig's taenia coli was loaded with normal (5 mm K) medium (1) containing 42K for 3 hours. During the last 30 minutes of loading period, hot 40 mm K medium was used when subsequent wash out was carried out with 40 mm K medium. After loading, the muscle was washed with non-radioactive medium for 5 seconds, and then washed successively with the same medium at 5-15 minute intervals. Eva porated washout solutions were counted with a GM counter. Two typical outflow curves are depicted in Fig. 1. An outflow curve was drawn from each series of washout, and each curve was analyzed graphically on assumption that the curve was multiple-exponential and was practically single-exponential approximately an hour after the start of washout (Fig. 1). Each curve consisted of three components both with 5 mm K and 40 mm K. The outflow rate constants of three com ponents are presented in Table 1, in comparison with those obtained in the previous work except ko which