Movements of radioactive potassium in isolated rat ganglia

摘要

1. Isolated rat superior cervical ganglia were continuously superfused with ⁴²K (or ⁸⁶Rb) solution and the amount of radioactivity taken up was monitored using scintillation counting.2. Entry of ⁴²K into the ganglia could be resolved into two components, one amounting to 83% of the total ⁴²K uptake, with a rate constant of 0·015 min^-1, and the other of 17% of the total, with a rate constant of 0·15 min^-1.3. With 6 mM-K in the bathing solution, the equilibrium uptake of ⁴²K after 4 hr corresponded to an intracellular concentration of 147 mM-K. Changes in the K concentration of the bathing solution (0·5-20 mM) had little effect on this value.4. Carbachol or nicotine caused a rapid net loss of ⁴²K. ⁴²K was recaptured on washing out the depolarizing agents, with a rate constant of about 0·3 min^-1. This recapture rate was slowed by ouabain, dinitrophenol, cyanide, mersalyl and by reducing the K concentration in the bathing solution.5. Efflux of ⁴²K from preloaded ganglia occurred with a rate constant of 0·017 min^-1. This rate was increased about sixfold by 180 μM carbachol in 6 mM-K but not in 150 mM-K suggesting that the increase in efflux was mainly a consequence of the depolarization caused by carbachol.6. ⁸⁶Rb fluxes and the effects of carbachol thereon were similar.