ION FLUXES AND TRANSFERENCE NUMBER IN SQUID AXONS

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Abstract
Squid giant axons were injected with K42 and isethionate-C14 over about 10-20 mm of length. Current was then passed through the injection capillary when this was centered in the injected region. Changes in efflux of the injected radioisotope were monitored in the sea water flowing from the injection chamber and the results showed that K+ carried essentially all of a depolarizing current. Neither Na+ nor isethionate" carried any measurable current; influx studies with Cl36 showed that this ion might carry [image] 4% of the current of depolarization. The following additional data were obtained during the course of the transference measurements: resting sodium and potassium effluxes and influxes, sodium efflux and net potassium loss during stimulation. These subsidiary data generally confirm previous conclusions by other investigators except that resting sodium influx, under certain experimental conditions, was several times lower than previously reported. The lower figure for sodium influx yields, under constant field assumptions, a value for PNa of 1.5 A/sec, a value comparable to that for frog sartorius muscle.