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- Title
Nephron heterogeneity in ischemic acute renal failure.
- Authors
Conger, John D.; Robinette, John B.; Kelleher, Stephen P.
- Abstract
Nephron heterogeneity in ischemic acute renal failure. To uncover the reasons for reported internephron heterogeneity in acute renal failure (ARF) serial micropuncture experiments in norepinephrine-induced ARF and and sham-infused control rats were carried out to investigate this phenomenon. Proximal tubular pressures (PT) were scattered at 24, 48, and 72 hr in ARF rats ranging from 4 to 42 mm Hg, but the majority were greater than the mean control values (10 ± 1 mm Hg). One week ARF PT were less variable than on previous days (5 to 17 mm Hg). The decreased variability was the result of a reduced number of PT values that were greater than controls. When single nephron filtration rates (SNGFR) were measured with spontaneous flow collections without maintaining the existent tubular pressures, results were widely scattered on each day. When SNGFR were measured at the existent PT, individual determinations were tightly clustered on each experimental day, clearly different from controls (all P < 0.001), and correlated closely with predicted values from whole kidney inulin clearance (all P < 0.001). Thus, existent internephron SNGFR was uniform in ARF rats and apparent heterogeneity, in large part, was attributable to an artifact of the tubular fluid collection technique. Despite the uniformity of SNGFR, values of PT ranging below as well as above controls, suggested that a mechanism in addition to tubular obstruction was operative in reducing SGNFR. Recoveries of microperfused 14C-inulin were similar to controls excluding significant backleak of tubular fluid. Glomerular filtration capacity (GFC) determined by performing tubular fluid collections at measured reductions in pressure (PD) from stop-flow varied as a function of the initial PT indicating that obstruction was the dominant pathogenetic factor in nephrons with the highest PT values, while glomerular dysfunction was the major pathogenetic mechanism in nephrons with the lowest PT values. Intermediate PT and GFC values represented nephrons with both tubular obstruction and glomerular dysfunction operating to reduce SNGFR.
- Subjects
ACUTE kidney failure; NORADRENALINE; KIDNEY diseases; KIDNEY tubules; INULIN
- Publication
Kidney International, 1984, Vol 26, Issue 4, p422
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1038/ki.1984.191