Carotenoid Compound Crocetin Improves Cerebral Oxygenation in Hemorrhaged Rats

Summary: The carotenoid compound crocetin has been shown to increase oxygen diffusivity in vitro. In the present study the effect of crocetin on tissue oxygenation was examined in the cerebral cortex of rats subjected to hemorrhage. Twelve male Sprague-Dawley rats were anesthetized with pentobarbital and ventilation was controlled (Paco2 = 33 mm Hg). A craniotomy was performed and the animals were hemorrhaged (20% of estimated total blood volume). Six of 12 animals then received a bolus of crocetin (2 U in 0.1 ml saline); the remaining animals received saline (0.1 ml i.v.) only. Values for mean arterial pressure, Po2, Pco2, pH, and hematocrit did not differ in rats that received either saline or crocetin. Tissue oxygen tension (Pao2) was measured at ~170 locations in the parietal cerebral cortex of each rat by a platinum-oxygen microelectrode technique. Results were compared by Pao2 frequency histograms. Crocetin as compared with saline treatment resulted in a right shift of the Pao2 frequency distribution and a significant decrease in the frequency of occurrence of low Pao2 values. The average of individual median Pao2 values was significantly greater in crocetin-treated animals as compared with those receiving saline (7.6 ± 1.7 vs. 3.2 ± 1.2 mm Hg, respectively). The results suggest that the carotenoid compound crocetin improves tissue oxygenation in the cerebral cortex of hemorrhaged rats.