Interstitial fluid dynamics in conscious renal hypertensive rats.

Abstract

Interstitial fluid pressure (IFP) was measured in conscious rats with one-kidney one-clip Goldblatt hypertension using implanted capsules. No significant differences in IFP were found between rats with hypertension of 3, 28, or 56 days duration and the one-kidney controls. To estimate interstitial compliance in the 28-day hypertensive and control rats, hyperosmotic albumin solution was infused intravenously. The subsequent transfer of tissue fluid into the intravascular space was associated with increased diuresis and decreased IFP. The changes in tissue fluid volume (TFV) were estimated from the changes in plasma volume and urine output. In the hypertensive rats 3 h postinfusion, TFV decreased by 36.3 +/- 2.9 ml/kg, and IFP decreased from -1.2 +/- 0.2 to -4.7 +/- 0.6 mmHg. In the normotensive rats TFV decreased by 36.7 +/- 2.7 ml/kg, and IFP decreased from -1.2 +/- 0.2 to -4.3 +/- 0.4 mmHg. Interstitial compliance, estimated from the regression of delta IFP and delta TFV, averaged 7.3 +/- 1.2 and 8.1 +/- 0.7 ml.kg-1.mmHg-1 (P greater than 0.5) in the hypertensive and normotensive rats, respectively. These results suggested that the rats with one-kidney one-clip Goldblatt hypertension had normal interstitial fluid dynamics.