Renal Responses to Acute Extracellular Fluid Volume Expansion after Decapsulation of the Kidney

Abstract

Summary

In the present study the importance of the kidney capsule in the renal responses to acute extracellular fluid (ECF) volume expansion was examined. Studies were performed 20 hours to 23 days after decapsulation of the left kidney. The increased rates of glomerular filtration (GFR), urine flow, sodium excretion and osmolar clearance during the ECF expansion were not significantly different in the kidneys with no capsules or reforming capsules as compared to the contralateral control kidneys with intact capsules. The present studies therefore demonstrated that decapsulation of the kidney does not affect the renal response to ECF expansion during the first 3 weeks after removal of the capsule. If intrarenal pressure is an important factor in the natriuretic response to ECF expansion, these decapsulation studies provide indirect evidence that the renal capsule is not an important determinant of intrarenal pressure during salt loading. While it has been suggested that renal decapsulation abolishes renal autoregulation, there was no such influence of decapsulation on the responses of the glomerular filtration rate during ECF expansion.