PT  - JOURNAL ARTICLE
AU  - Y Matsushima
AU  - M Gemba
TI  - Stimulatory action of verapamil on transport of organic acids in rat kidney cortical slices.
DP  - 1982 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 452--457
VI  - 222
IP  - 2
4099  - http://jpet.aspetjournals.org/content/222/2/452.short
4100  - http://jpet.aspetjournals.org/content/222/2/452.full
SO  - J Pharmacol Exp Ther1982 Aug 01; 222
AB  - 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 also stimulated by verapamil. D600, 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 degrees C. On the other hand, the preincubation of the slices with verapamil at 0 degrees C did not alter the PAH accumulation. Oxygen consumption and ATP content in the slices and microsomal (Na+ + K+)adenosine triphosphatase activity were not affected by verapamil. Verapamil enhanced a Na+ gradient to some degree. however, 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. These results suggest that 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+)adenosine triphosphatase activity.