Functional and hemodynamic adaptation to progressive renal ablation.

Abstract

Removal of renal tissue stimulates functional and anatomical adaptation in the remaining renal parenchyma. Since recent studies have demonstrated no apparent limitation in compensatory growth following progressive surgical ablation, experiments were performed to determine the changes in glomerular filtration rate and renal blood flow. After removal of 50% of the renal mass mean nephron glomerular filtration rate increased 60%, and after ablation of 75% of the renal tissue it increased 150%. These changes paralleled the increases in renal growth under the same conditions. In comparison, mean glomerular blood flow rose 90% and 240% after 50% and 75% nephrectomy, respectively; these changes in relation to the changes in glomerular filtration rate resulted in a progressive fall in the filtration fraction. Intrarenal blood flow distribution was examined with labeled microspheres. The marked increase in renal blood flow after surgical ablation was characterized by a disproportionate rise in blood flow to the inner cortex. The present investigation, therefore, describes the remarkable functional changes that occur as overall glomerular filtration rate declines and provides further insight into the mechanism responsible for maintaining water and electrolyte homeostasis after loss of functioning renal mass. KEY WORDSrenal blood flow compensatory adaptation rat mean nephron blood flow mean nephron glomerular filtration rate• Remarkable compensatory changes in renal mass and function occur following surgical removal of renal tissue and after damage by some disease processes. Although most studies have examined the contralateral kidney after unilateral nephrectomy, recent experiments have demonstrated that the extent of compensatory renal adaptation correlates directly with the amount of renal tissue removed (1). Although adaptive changes in renal function are responsible for maintaining water and electrolyte homeostasis (2), the factors that control and influence such changes are not well understood. Therefore, the relationship between compensatory increases in glomerular filtration rate and renal hemodynamics following progressive ablation were studied.Methods Experiments were performed on male Sprague-Dawley rats (Charles River Breeding Laboratories) weigh- This work was supported by U. S. Public Health Service Grants AM0567602 and TIAM5015 from the National Institutes of Health, U. S. Public Health Service Grant HL-13647 from the National Heart and Lung Institute, the Connecticut Heart Association, and the American Heart Association.Dr. Hayslett is an Established Investigator of the American Heart Association.Received August 21, 1974. Accepted for publication November 6, 1974. 286ing 150-200 g at the beginning of the study. Three groups were prepared under ether anesthesia. Group A rats served as controls, and a sham operation was performed on their right kidneys. Group B rats underwent 50% ablation of the total renal mass by right nephrectomy. In group C, approximately 70-75% of the total renal mass was rem...

Metabolic and functional consequences of inhibiting adenosine deaminase during renal ischemia in rats.

“…At the end of this insult the catheters were removed and the animal was allowed free access to food and water. Kidney function was determined by inulin clearance 24 h after the injury (18). The animals were anesthetized with Inactin (80 mg/kg, i.p.)…”

Ultrastructural changes and nestin expression accompanying compensatory renal growth after unilateral nephrectomy in adult rats

“…[13][14][15] After unilateral nephrectomy, the major instant functional adaptation is a gradual increase in the mean glomerular filtration rate. 16,17 This increase is initiated due to the variations in renal hemodynamics, such as an increased renal blood flow coupled with decreased afferent arteriole resistance caused by renal cortical vasodilatation. 16,[18][19][20] An increase in fractional excretion of water and solutes following compensatory adaptations in tubules is due to a reduction in the fractional reabsorption of sodium and water, increased potassium secretion or enhanced flow of tubular fluid.…”

“…16,17 This increase is initiated due to the variations in renal hemodynamics, such as an increased renal blood flow coupled with decreased afferent arteriole resistance caused by renal cortical vasodilatation. 16,[18][19][20] An increase in fractional excretion of water and solutes following compensatory adaptations in tubules is due to a reduction in the fractional reabsorption of sodium and water, increased potassium secretion or enhanced flow of tubular fluid. [21][22][23][24] Adaptive changes in glomeruli and tubules in response to nephron deficiency can increase the risk of hypertension and renal disease in the long run.…”

Hemodynamic Adaptation to Reduced Renal Mass in Early Postnatal Development

“…In the adult rat subjected to uninephrectomy or ablation of 75% of renal mass, zonal perfusion shifted from outer to deeper nephrons when compared to sham-operated controls (12). Similarly, ablation of 75% of renal mass in the 2-month-old dog resulted in augmented glomerular perfusion of the deep cortex without change in OC glomerular perfusion (3).…”

“…Renal blood flow increases with normal development (9) and as a result of compensatory renal hypertrophy at any age (12). In the guinea pig uninephrectomized at birth, there is an accelerated increase in superficial single nephron glomerular filtration rate by 10 days of age (5).…”