Movements of radioactive potassium in isolated rat ganglia

Abstract

SUMMARY1. 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-, and the other of 17 % of the total, with a rate constant of 0-15 min-.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-'. 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-'. This rate was increased about sixfold by 180 /SM 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.

Muscarinic Receptors in Rat Sympathetic Ganglia

“…The resting rate coefficient for 86Rb+-efflux into normal Krebs solution attained a 'basal' value of between 0.01 and 0.02 min-after 60 min or so, in agreement with previous observations on this tissue using both 86Rb+ and 42K' (Scholfield, 1977a). Reduction or elevation of external [K+] over the range 2 to 60 mm reduced or increased the efflux rate coefficient respectively (Figure 12a).…”