LITHIUM-CARBONATE DECREASES ULTRAFILTRATION RATES IN AN EXPERIMENTAL-MODEL OF PD

Animal studies have shown increased fluid absorption from the peritone al cavity following intraperitoneal (ip) vasopressin. Lithium is known to antagonize vasopressin effects on fluid absorption in kidney dista l nephrons. The aim of the present study was to see whether lithium-co ntaining exchanges increase the ultrafiltration rates (UF) during peri toneal dialysis (PD) in rats. PD was carried out in 6 Sprague-Dawley r ats with 1.5% dextrose-containing PD solution using 15-ml volumes. Eac h exchange (ex) took 1 min for inflow, 4 mins for outflow and 25 mins for dwell. All rats underwent 9 consecutive half-hourly exs. During ex s 4-6 lithium carbonate 2.5 mM was added to the PD solution. During li thium-containing exs significant increases in the glucose absorption r ates (3.9 +/- 7.8 vs 37.5 +/- 8.1 mg/ex; p=0.025) were associated with significnat reductions in the UF (3.03 +/- 0.25 vs 1.78 +/- 0.12 ml/e x; p=0.005). in conclusion, the isolated increase in glucose absorptio n without increases in the dialysate protein concentration with ip lit hium, may suggest either a selective increase in size of the pores wit h a mean dimater near that of the glucose molecule or enhanced lymphat ic absorption. ip lithium did not increase the UF in a rat model of PD .