Abstract
Transmural electrical properties of the isolated rabbit iris-ciliary body (I-CB) were measured in Ussing-Zerahn-type chambers. Control p.d. across the preparation was −1·2±0·1 mV, with the ciliary process (aqueous)-side consistently negative with respect to the ciliary body (blood)-side and the short-circuit current (SCC) was 7·9±0·6 μA cm −2. Bilateral bathing solution substitutions demonstrated absolute requirements for the presence of Na +, K + and HCO 3 − for the maintenance of the p.d. Addition of 5 × 10 −5 m ouabain to the aqueous-side chamber increased the p.d. and SCC initially, with a subsequent decline to zero. Only a declining phase was observed when ouabain was added to the blood-side. Ouabain inhibited oxygen consumption by 28% in Tyrode's solution. Respiratory rate was also approximately 28% lower in Na +-free and K +-free Tyrode's solution and ouabain had no additional inhibitory effect in either of these two solutions. Thus the biphasic effect of ouabain on the electrical parameters cannot be explained by a toxic effect but rather as a selective inhibition of the Na +-, K +-pump. Our results indicate that Na +-, K +-ATPase activity and the presence of HCO 3 − are required for active ion transport in this preparation.
Published Version
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