A monovalent ion-selective cation current activated by noradrenaline in smooth muscle cells of rabbit ear artery |
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Authors: | Q Wang R C Hogg W A Large |
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Institution: | (1) Department of Human Anatomy, South Parks Road, OX1 3QX Oxford, UK;(2) Department of Child Health, Centre for Research into Human Development, Ninewells Hospital and Medical School, University of Dundee, DD1 9SY Dundee, UK |
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Abstract: | We have studied chloride influx and efflux in a highly purified preparation of type n cells freshly isolated from adult guinea-pig lung using 36Cl–. Chloride uptake was time-dependent, saturable (Km<10 mM) and was inhibited by 4,4 -diisothiocyanatostilbene-2,2 -disulphonic acid (DIDS; Ki 80 M). In the absence of external chloride (substituted by gluconate), 36Cl– uptake exhibited an overshoot above equilibrium. The rate of 36Cl– entry was strongly inhibited by addition of external nitrate; sulphate was a weaker inhibitor. 36Cl– efflux was stimulated by external bromide > bicarbonate chloride citrate; and was inhibited by proprionate > acetate > oxalate. Although the chloride channel blocker 4-nitro-2-(3-phenylpropylamino)benzoate (0.14 mM) caused an inhibition, 36Cl– influx did not appear to be electrogenic. These data are compatible with the existence of a substantial electroneutral anionexchange pathway for chloride transport in freshly isolated adult type II pneumocytes. |
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Keywords: | Type II pneumocytes Chloride transport Anion exchange Epithelial transport |
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