HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Thomas, R. C. Search for Related Content PubMed PubMed Citation Articles by Thomas, R. C.

1. Recessed-tip Na⁺-sensitive micro-electrodes were used to measure [Na⁺]_i continuously in snail neurones for experiments lasting up to several hours. The average resting [Na⁺]_i in twenty-two cells was 3·6 mM.

2. Inhibition of the Na pump by ouabain caused [Na⁺]_i to increase at an average rate of 0·54 m-mole/min. This corresponds to a passive influx of Na quantitatively similar to that observed in squid axons.

3. Changing external K over the range 1-8 mM had little effect on [Na⁺]_i, but K-free or 0·25 mM-K Ringer caused a rise in [Na⁺]_i.

4. Increasing membrane potential by up to 90 mV caused an increased influx of Na, but did not inhibit the pump.

5. Reducing external Na caused a decrease in [Na⁺]_i but did not affect the pump rate at a given [Na⁺]_i. The pump rate at low [Na⁺]_i was proportional to [Na⁺]_i minus a threshold value of about 1 mM.

6. The Na pump appeared still to be electrogenic at subnormal rates of activity.

7. It is concluded that, given sufficient external K, the rate of the Na pump depends principally on [Na⁺]_i. Changes in external Na or membrane potential appear to affect the pump only indirectly, by changing the Na influx and thus [Na⁺]_i.

This article has been cited by other articles:

				R. C. Thomas The Effects of HCl and CaCl2 Injections on Intracellular Calcium and pH in Voltage-clamped Snail (Helix aspersa) Neurons J. Gen. Physiol., September 30, 2002; 120(4): 567 - 579. [Abstract] [Full Text] [PDF]