Electrolyte Changes in Renal Cortex,Inner Medulla and Papilla in Renal Artery Clamp Hypertension 1

Abstract

Conclusion

Chronic hypertension was produced in rats by renal artery clamps and the renal tissues (cortex and a combined sampling of papilla and inner medulla) were examined for water, sodium, potassium content, and osmolarity.

In hypertensive rats with a contralateral untouched kidney, the cortex on the side bearing the clamp showed evidence of volume depletion compared to the opposite intact side, i.e., significance tests showed a decreased water content, an unchanged sodium, and increased potassium content per kilo of tissue water; a decreased sodium and an unchanged potassium content when expressed per unit of dry weight. In the three hypertensive rats in which the contralateral kidney was excised after placement of the renal artery clamps, no significant difference was noted from the cortex of control uninephrectomized animals.

Unlike the cortex, tissue from the inner medulla and papilla did not exhibit a difference between the clamped and the untouched kidney with respect to water or sodium content. The potassium content of the clamped kidney was reduced as compared to its opposite untouched kidney (5% level) and the osmolarity of the untouched kidney was reduced as compared to controls (5% level).

Although both kidneys of clamp bearing rats contained equal amounts of sodium in the papilla and inner medulla, both contained significantly less than control rats (5% level), as did similar tissue from uninephrectomized rats with a clamped kidney (5% level). The findings suggest that the reduction is not due exclusively to washout and is independent of perfusion pressure.

We are indebted to Dr. Agnes Berger of the Columbia School of Public Health Administrative Medicine for assistance with the statistical analyses.