1. The effects of ischaemic preconditioning (IP) on renal function, haemodynamics and lipid peroxidation in the rat ischaemia-reperfused kidney model were examined. 2. In Wistar male rats, application of a single or three periods of 5 min bilateral renal ischaemia was performed prior to 30 min bilateral ischaemia and 90 min reperfusion (IR). The glomerular filtration rate (GFR) was estimated in terms of inulin clearance. Fractional excretion of sodium (FE(Na)) and lithium (FE(Li)), indicating total and proximal tubular sodium handling, respectively, was also measured and renal blood flow was monitored throughout the experiment. In addition, renal lipid peroxidation (LPO) levels in reperfused kidneys were evaluated. 3. A 2.8-fold increase in recovery of GFR (P < 0.005), a 50% reduction in FE(Na) (P < 0.005) and a 40% decrease in FE(Li) (P < 0.05) after IR resulted from the single period of 5 min IP. Renal blood flow was also higher than that in the control group (P < 0.01). No change of LPO levels was observed. 4. We conclude that IP may have an ability to ameliorate reperfused renal function and haemodynamics with a suitable period of preconditioned ischaemia, although this effect is independent of LPO.

Abstract. Atrial natriuretic peptide (ANP) has been shown to have the potential to restore renal function after ischemic injury, an underlying component of endotoxin (Et)-induced acute renal failure, and is known to counteract renal sympathetic nerve activity in renal function. We have recently found that renal denervation restores the Et-induced renal dysfunction. The purpose of this study was to examine effects of ANP infusion on the Et-induced acute renal failure in the absence of renal nerves. Ten to 14 days after bilateral renal denervation (DNX), Wistar rats (250 to 300 g body wt) were used in the acute experiment.Rats with intact renal nerves (INN) served as controls. Following control clearance measurements, rats were intravenously injected with 4 mg/kg Et (Escherichia coli, 055: B5). During endotoxemia, rats were infused with 10 µg/kg/h ANP or saline vehicle. Et injection reduced the glomerular filtration rate (GFR) significantly in saline-infused INN and DNX rats. ANP infusion restored the greatly reduced GFR to the pre-endotoxemia level in DNX rats but not in INN rats. There was significant difference between the ANP-and saline-infused DNX rats in the percentage change relative to the basal GFR value during the ANP infusion period. ANP infusion did not improve the hyponatriuresis and oliguria after Et administration, which is independent of renal nerves. In conclusion, ANP infusion has a minor reno-protective effect in rats with Et-induced acute renal failure in the absence of the renal nerves.