Despite the wide use of laparotomy to study kidney function, the possi
ble influence of this procedure on systemic and renal parameters in se
ptic rats is unknown, We studied this in anesthetized Wistar rats with
and without endotoxin shock (1 h Escherichia coil O127.B8: 8 mg . kg(
-1) infusion). We also compared clearance of creatinine and inulin to
measure glomerular filtration rate (GFR). Laparotomy attenuated the en
dotoxin-induced decrease in cardiac output and abolished the increase
in systemic and renal vascular resistance, while renal plasma flow was
maintained. Better perfusion in other organs as well was indicated by
a more gradual increase in arterial lactate concentration and less in
testinal damage. By contrast, GFR decreased considerably during endoto
xemia, irrespective of laparotomy. This change in GFR could be reliabl
y assessed using creatinine clearance. The ratio of creatinine-to-inul
in clearance averaged between .5 and .75. Renal ATP content did not ch
ange and the endotoxin-induced increase in the number of granulocytes
lodged in glomeruli was not affected by laparotomy. in conclusion, our
study indicates that laparotomy significantly influences the vascular
effects caused by endotoxin. Laparotomy also revealed an effect of en
dotoxin on GFR, independent of renal blood flow.