M. Halpenny et al., The effects of fenoldopam on renal blood flow and tubular function during aortic cross-clamping in anaesthetized dogs, EUR J ANAES, 17(8), 2000, pp. 491-498
Postoperative renal impairment is a recognized complication of infrarenal a
ortic cross-clamping. Fenoldopam, a selective dopamine agonist, may increas
e renal blood flow and decrease tubular oxygen consumption. The objective o
f this study was to quantify the effects of fenoldopam (0.1 mu g kg(-1) min
(-1)) on renal blood flow and renal tubular function in anaesthetized dogs
that have undergone aortic cross clamping. Eight labrador dogs were selecte
d to receive either saline or fenoldopam (0.1 mu g kg(-1) min(-1)) intraven
ously. Arterial pressure, heart rate, renal blood flow, urinary output, fra
ctional excretion of sodium, creatinine clearance and lithium clearance wer
e measured (a) prior to infusions of saline or fenoldopam (b) 1 h after com
mencing the infusion (c) during a 90-min period of infrarenal aortic cross-
clamping with concurrent infusion of fenoldopam or saline and (d) for 1 h a
fter simultaneous aortic declamping and discontinuation of the infusions. T
here was no haemodynamic instability upon commencing the infusion of fenold
opam (0.1 mu g kg(-1) min(-1)). Creatinine clearance (2.03+/-0.5-2.45+/-0.3
mL min(-1) kg(-1) (mean+/-SD)), urine output (0.23+/-0.16-0.35+/-0.23 mL m
in(-1) (mean+/-SD)), and fractional excretion of sodium (0.7+/-0.52-1.3+/-0
.73%(mean+/-SD)) increased (P < 0.05), following commencement of the fenold
opam infusion. Fractional excretion of sodium (1.2+/-0.7% (mean+/-SD)) and
urine output (0.36+/-0.21 mL min(-1) (mean+/-SD)) were maintained during th
e aortic cross-clamp period (P < 0.05). Renal blood flow increased when the
fenoldopam infusion was commenced (145+/-43.3-161+/-39.2 mL min(-1) (mean/-SD)) and remained greater than baseline during the aortic cross-clamping
period (152+/-44 mL min(-1) (mean+/-SD)), although these increases did not
reach statistical significance. The mast striking abnormalities observed by
electron microscopy were marked disruption of the microvillus brush border
in proximal tubules, vacuolation and separation of epithelial cells on bas
olateral infolds. The changes were similar in the two groups. In conclusion
fenoldopam (0.1 mu g kg(-1) min(-1)) may have renoprotective effects which
persist during infrarenal aortic cross clamping.