The effect of unilateral nephrectomy on glomerular filtration rate, fractional clearance of urinary electrolytes, compensatory renal growth, and plasma growth hormone concentration in late gestation in the fetal lamb

Author

Hilary Kay Matthews

Date of Award

12-1996

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Comparative and Experimental Medicine

Major Professor

Frank M. Andrews

Committee Members

Roger C. Carroll, Eddie S. Moore, Susan E. Mulroney, J. Erby Wilkinson

Abstract

It is well known that a reduction in renal mass results in compensatory renal growth (CRG) and functional adaptation of the remaining kidney. Age-related differences in response to unilateral nephrectomy (UNX) have been demonstrated. Immature animals respond primarily with hyperplastic CRG and have greater functional adaptation. Adult animals respond primarily with hypertrophic CRG and do not have as complete functional adaptation. The initiating mechanism(s) of the response to UNX remains elusive. There are a paucity of conflicting reports describing the response of the fetus to UNX, and there are no reports examining possible initiating mechanisms of the response. A study was undertaken to examine the response of the late gestational (> day 130) ovine fetus to UNX and to examine the role of growth hormone (GH) as a possible initiator of compensatory adaptation. Glomerular filtration rate (GFR) in mis/min or mis/min/kg body weight was significantly greater in sham operated (control) versus UNX animals 24 and 72 hours post-UNX. There was no difference in GFR in mis/min/gm kidney weight between the two groups at 24 and 72 hours post-UNX. Fractional clearance of urinary electrolytes was increased (not significantly) 24 hours post-UNX versus control animals. By 72 hours post-UNX, values for fractional clearance of electrolytes had decreased and were similar to control animals. Urine production 24 and 72 hours post-UNX was not different from control animals. No significant increase in remnant kidney weight was found 24 or 72 hours post-UNX versus control animals. By 72 hours post-UNX remnant kidney weight did trend toward an increase (8.5%) over normal growth during this time. Protein and DNA content of the remnant kidney as a measure of hypertrophy and hyperplasia, respectively, increased over extant kidney values by 72 hours post-UNX. Mean plasma GH concentration, total GH secreted, and the pulsatile nature of GH secretion was not different from control animals 24 or 72 hours post-UNX. It appears that the late gestational ovine fetus can undergo functional adaptation and CRG following UNX, but the response is of a lesser magnitude compared with the postnatal animal, and this adaptation appears to be GH independent.

Recommended Citation

Matthews, Hilary Kay, "The effect of unilateral nephrectomy on glomerular filtration rate, fractional clearance of urinary electrolytes, compensatory renal growth, and plasma growth hormone concentration in late gestation in the fetal lamb. " PhD diss., University of Tennessee, 1996.
https://trace.tennessee.edu/utk_graddiss/9810