INHIBITION OF CALCIUM-ABSORPTION IN THE CORTICAL THICK ASCENDING LIMB OF HENLE LOOP BY FUROSEMIDE

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 221  (3) , 815-819
Abstract
The effect of luminal furosemide on Ca transport across the cortical thick ascending limb of Henle''s loop was studied. Cortical thick ascending limbs were dissected from rabbit kidneys and perfused in vitro. Ca concentrations in perfused and collected tubule fluids were measured by continuous-flow microcolorimetry. Tubules were perfused at slow flow rates and parathyroid hormone was added to the bathing solution to maximize the difference between perfusate and collectate Ca concentrations. Furosemide simultaneously and reversibly inhibited the lumen-positive transepithelial voltage and Ca absorption. In the presence of furosemide perfusate-minus-collectate, Ca concentration difference was smallest under conditions that minimized the residual transepithelial voltage. Apparently, furosemide inhibits Ca absorption in the cortical thick ascending limb of Henle''s loop by reducing the lumen-positive transepithelial voltage that drives passive Ca2+ transport.