Acute decrease in renal microvascular [Po.sub.2] during acute normovolemic hemodilution

Large differences in the tolerance of organ systems to conditions of decreased [O.sub.2] delivery such as hemodilution exist. The kidney receives ~25% of the cardiac output and [O.sub.2] delivery is in excess of the oxygen demand under normal circumstances. In a rat model of acute normovolemic hemodilution (ANH), we studied the effect of reduced hematocrit on renal regional and microvascular oxygenation. Experiments were performed in 12 anesthetized male Wistar rats. Six animals underwent four steps of ANH (hematocrit 25, 15, 10, and phosphorescence quenching; tissue oxygenation; renal microvascular oxygenation; kidney; oxygen consumption