| Autor: |
Herrera, Francisco, Rodriguez, Arlec, López, Ildemaro, Weitzmann, Henny, Zanders, I. |
| Zdroj: |
Journal of Comparative Physiology B: Biochemical, Systemic & Environmental Physiology; Jul1986, Vol. 156 Issue 4, p591-597, 7p |
| Abstrakt: |
Maintenance of intracellular ion contents and their relations to transmembrane potential were studied in tentacles of Condylactis gigantea. Tentacles leached at 2°C in 10 mMK and 2 mM K artificial seawaters (10K ASW and 2K ASW) with and without 2 MM ouabain, and in 0K ASW, lost cell K and gained Na. Rewarming to 25°C in 10K ASW resulted in a marked accumulation of K and extrusion of Na in tentacles leached in 10K ASW and in 0K ASW. Initial rate of Na extrusion was twice the initial rate of K accumulation, suggesting a pump coupling ratio of 2. In tentacles leached and rewarmed in 2K ASW, no net reaccumulation of K and little net extrusion of Na was observed; i.e., the pump just kept pace with the leaks. Ouabain inhibited K reaccumulation and Na extrusion. This effect was less marked in 10K ASW than in 2K ASW confirming, in anemone tentacles, the well documented ouabain-K antagonism observed in other systems. In no case did K/K equal Cl/Cl; therefore, the distribution of these ions did not fit a Donnan distribution. Transmembrane potential difference was −22±3 mV in 10K ASW at 25°C. It fitted a modified Nernst equation which includes the pump coupling ratio and a Na to K permeability ratio of 0.31. A moderately high permeability of the cell membrane to Na, and a ouabain and K sensitive ion pump, exchanging 2 Na for 1 K, appear to be responsible for the observed ionic distribution and transmembrane potential in anemone cells. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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