Aminoguanidine does not influence tissue extravasation of albumin in endotoxaemic rats

Background: It is generally maintained that protein and fluid are lost from the circulation under septic conditions. The role played by an increased p roduction of nitric oxide, by the inducible nitric oxide synthase (iNOS), i n this process is unclear Methods: Chloralose anaesthetised male Wistar rats received E. coli lipopol ysaccharide (LPS), 3 mg kg(-1) i.v., and were studied for 5 h. Mean arteria l pressure (MAP) and heart rate (HR) were monitored and haematocrit (Hct) w as determined intermittently Tissue plasma volume and tissue clearances of radiolabelled albumin over the last 2 h of the experiment were determined b y a double-isotope method. In 8 rats, 2 h after LPS, aminoguanidine, an iNO S selective blocker, was given i.v. at a dose of 5 mg kg(-1). This was foll owed by a continuous infusion for the duration of the experiment; altogethe r 20 mg kg(-1) was administered. In the control group (n = 8), a correspond ing volume of saline was infused. Results: Aminoguanidine did not significantly influence Hct, MAP and HR, as evidenced by inter-group comparisons (Mann-Whitney test). Tissue plasma cl earances of albumin and tissue plasma volume were similar in both groups. Conclusion: Aminoguanidine at 20 mg kg(-1) did not reverse the haemodynamic changes induced by LPS. Neither did the drug affect the tissue plasma clea rance of albumin or the tissue plasma volume.