The Efflux of Potassium from Electroplaques of Electric Eels

1. T h e m o v e m e n t of l abe led potass ium ions has been measured across the inne rva ted m e m b r a n e s of single isolated e lect roplaques , ob ta ined f rom the organ of Sachs of Electrophorus electricus, m o u n t e d in an a p p a r a t u s which al lowed a separa te washing of the two membranes . 2. Equa t ions have been der ived for a 3 c o m p a r t m e n t system in series in which t racer from a large pool in one outer c o m p a r t m e n t is collected in the o ther outer compa r tmen t . T h e a m o u n t of un labe led ion in the midd le c o m p a r t m e n t m a y be ca lcu la ted and also the fluxes across the two membranes . 3. T h e flux of potass ium across the innerva ted m e m b r a n e s of rest ing cells in a s teady state was be tween 700 to 1000 #/zmoles/cm.2/sec. and was unaffected by dtubocurar ine . 4. Di rec t s t imula t ion of e lec t roplaques wi th external electrodes caused an increase in the effiux of potass ium from the innerva ted m e m b r a n e of 5 to 8 /~/~moles/cm.~/impulse, which was unaffected by dtubocurar ine ; no change occur red in the efflux across the noninnerva ted membrane . 5. I t is conc luded tha t the discharge of e lec t roplaques is a ccompan ied by a small ou tward m o v e m e n t of potass ium ions across the innerva ted m e m b r a n e of the same order of magn i tude as tha t found on exci ta t ion of squid g ian t axons. T h e d a t a show a basic s imi lar i ty of potass ium movements across these two ent i re ly different types of conduc t ing membranes and suggest tha t this p h e n o m enon m a y be a genera l feature of bioelectr ic currents p r o p a g a t i n g an ac t ion potential .