AJP - Regulatory, Integrative and Comparative Physiology, Vol 269, Issue 5 1002-R1008, Copyright © 1995 by American Physiological Society
Single-nephron adaptations to partial renal ablation in cats
S. A. Brown and C. A. Brown
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
To evaluate remnant nephron hyperfiltration, cats underwent sham surgery
(group 1, n = 6) or three-fourths nephrectomy (group 2, n = 6). Four to six
weeks later, micropuncture studies demonstrated increases (P < 0.01) of
single-nephron glomerular filtration rate (SNGFR) in group 2 (28.1 +/- 2.8
vs. 56.0 +/- 5.9 nl/min). In group 2 the mean estimated glomerular
capillary pressure of 74.0 +/- 1.7 mmHg exceeded (P < 0.01) the value
for group 1 (62.6 +/- 1.4 mmHg). The mean effective filtration pressure
(EFPm) for group 2 (28.7 +/- 3.1 mmHg) was greater (P < 0.05) than that
in group 1 (20.8 +/- 1.9 mmHg). Similarly, the mean ultrafiltration
coefficient (Kf) in group 2 of 2.03 +/- 0.24 nl.min-1.mmHg-1 exceeded (P
< 0.05) the corresponding value for group 1 of 1.35 +/- 0.06
nl.min-1.mmHg-1. Morphological studies demonstrated glomerular enlargement
and mesangial matrix expansion in group 2 (P < 0.05). Proteinuria, as
assessed by the urine protein-to-creatinine ratio, was increased (P <
0.05) after partial renal ablation. These results demonstrate that
increases in SNGFR in feline remnant nephrons occur in association with
glomerular hypertension, glomerular hypertrophy, expansion of mesangial
matrix, and proteinuria, and furthermore, that the observed increases in
SNGFR are attributable to an augmentation of EFPm and Kf.
