Jd. Conger et al., RESPONSES TO HEMORRHAGIC ARTERIAL-PRESSURE REDUCTION IN DIFFERENT ISCHEMIC RENAL-FAILURE MODELS, Kidney international, 46(2), 1994, pp. 318-323
Renal blood flow (RBF) autoregulation has been found to be impaired in
both norepinephrine (NE) and renal artery clamp (RAC) rat ischemic ac
ute renal failure models. However, the decline in RBF at the normal lo
wer limit of autoregulation is greater in NE-ARF. The present study wa
s designed to determine if this difference in autoregulatory profiles
has potential functional and morphologic significance. After demonstra
ting a fall in RBF to renal perfusion pressure reduction to 90 mm Hg t
hat was twofold more in one week NE- than RAC-ARF (p < 0.001), separat
e rats of both ischemic ARF types with nearly identical levels of azot
emia and glomerular filtration rate reduction and sham-ARF rats were s
ubjected to four-hour controlled reduction in mean arterial pressure t
o 90 by transient phlebotomy at one week. On day 9, two days after mea
n arterial pressure reduction, blood urea nitrogen (BUN), serum creati
nine (S-Cr) and creatinine clearance (C-Cr) showed continued improveme
nt in RAC-ARF, but there were significant increases in BUN (46 +/- 22
to 72 +/- 10 mg/dl) and S-Cr (1.2 +/- 0.2 to 1.5 +/- 0.2 mg/dl) and a
decline in C-Cr (0.434 +/- 0.127 to 0.334 +/- 0.079 ml/min) in the NE-
ARF group (all P < 0.02). The mean sum of scores of morphologic indice
s of ARF was higher in NE- than RAC-ARF kidneys of rats sacrificed on
day 9 but interstitial edema was the only individual index that was wo
rse in NE-ARF. By day 14, function parameters had improved in both ARF
groups, but BUN remained significantly higher in NE-ARF than the RAC-
ARF group (P < 0.01). It is concluded that there is a distinct differe
nce in susceptibility to recurrent injury and azotemia in NE- and RAC-
ARF which is likely related to differences in maintenance phase renova
scular reactivity in these two ischemic ARF models.