STIMULATORY ACTION OF VERAPAMIL ON TRANSPORT OF ORGANIC-ACIDS IN RAT-KIDNEY CORTICAL SLICES

  • 1 January 1982
    • journal article
    • research article
    • Vol. 222  (2) , 452-457
Abstract
Effect of verapamil on the organic acid transport was examined with rat kidney cortical slices. Verapamil increased the initial rate of p-aminohippurate (PAH) uptake, markedly enhanced its maximal accumulation under steady-state conditions and depressed the efflux of PAH. The accumulation of urate was stimulated by verapamil. D600 [methoxy verapamil], a derivative of verapamil, showed the same effect as verapamil with regard to the stimulation of PAH accumulation. Kinetic studies revealed that verapamil resulted in an increase in the Vmax of the transport of PAH. The apparent Km remained essentially constant. The PAH accumulation was enhanced by aerobic preincubation of the slices with verapamil at 37.degree. C. The preincubation of the slices with verapamil at 0.degree. C did not alter the PAH accumulation. O2 consumption and ATP content in the slices and microsomal (Na+ + K+) ATPase activity were not affected by verapamil. Verapamil enhanced a Na+ gradient to some degree. The PAH accumulation in the presence of verapamil and ouabain was increased approximately the same amount as in the absence of these drugs regardless of the dissipation of the Na+ gradient by ouabain. Verapamil accumulated by the slices stimulates the PAH uptake and its stimulatory action cannot be explained by the increase in the Na+ gradient and stimulation of (Na+ + K+) ATPase activity.

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