The temperature dependence of chloride fluxes in the squid giant axon

V. Scruggs, D. Landowne

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The influx and efflux of radioactive chloride was measured in intact squid giant axons. In the resting axon the rate of efflux was 2.8 x 10-4 min-1 at room temperature. When the temperature was decreased the efflux decreased with a Q10 of 1.3. There was no detectable extra efflux associated with nerve impulses. The resting influx at room temperature was 14 p moles/cm2-sec and this decreased as the temperature was lowered. The Q10 for the resting influx was found to be 2.4. There was an extra influx of chloride associated with nerve impulses of 0.08 p moles/cm2-imp at room temperature and this increased as the temperature was lowered with a Q10 of 1/1.3. The ratio of the resting fluxes (influx/efflux) at low temperatures approaches what would be expected for independent, passive movement of the ion whereas at room temperature the ratio is clearly too large. The high temperature dependence of the resting influx and the flux ratio calculations support the idea that there is an inwardly directed active transport mechanism for chloride ions in the squid axon membrane. The low temperature dependence of the extra chloride influx associated with nerve impulses is consistent with the low temperature dependence of the extra fluxes of sodium and potassium.

Original languageEnglish (US)
Pages (from-to)126A
JournalBiophysical journal
Issue number2 II
StatePublished - Jan 1 1975

ASJC Scopus subject areas

  • Biophysics


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