An increase in red blood cells (RBCs) is believed to improve exercise performance, because RBCs transport O 2 from the lungs to the tissues and deliver metabolically produced CO 2 to the lungs for expiration. In this study, we examined the effects of increased or decreased RBCs on exercise performance in mice. In order to vary the volume percentage of RBCs in blood (hematocrit levels), trained FVB mice were administered darbepoetin alfa (DPA), a long-acting erythropoiesis-stimulating agent, or phenylhydrazine (PHZ), a reagent inducing hemolytic anemia. The exercise performance was evaluated using a forced swimming pool. The administration of DPA or PHZ caused a significant increase or decrease in hematoctit levels, respectively. However, the partial improvement in exercise performance due to increased RBCs was observed only when higher intensity exercise was applied to mice whose hematocrit levels exceeded 70%. In addition, the decrease in exercise performance due to decreased RBCs was limited, even when the hematocrit levels was about 35%. These results suggested that the increase or decrease in RBCs had little effect on exercise performance in mice.
We previously reported that brotizolam, a benzodiazepine analog, but not suvorexant, an orexin receptor antagonist, delayed the recovery from isoflurane anesthesia in ICR mice. However, the effects of hypnotics can be affected by circadian rhythm. Using ICR mice and three inbred strains (sighted C57BL/6J and blind FVB/N and C3H/HeN mice), locomotor activity was measured during every 6 hours from zeitgeber time (ZT) 0, and the effects of brotizolam or suvorexant on isoflurane anesthesia were compared during light period and dark period. Although the locomotor activities were highest at ZT12-18 in all the strains examined, there was no significant difference between the activities at ZT0-6, ZT6-12, and ZT18-24 in the blind mice. In ICR mice, the delayed effect of brotizolam on recovery from isoflurane anesthesia in dark period was weaker than that in light period, while the delayed effect of suvorexant was observed only in dark period. In C57/BL6J mice, the delayed effect of brotizolam was remarkable, compared to other strains, and stronger in light period than in dark period, while the delayed effect of suvorexant was observed in both light and dark periods. In the blind mice, the delayed effect of brotizolam was slightly, but significant, and similar in both light and dark periods, while suvorexant did not influence the recovery from isoflurane anesthesia in both periods. These results suggested that the effects of hypnotics was affected by circadian rhythm, and that the daily light-dark stimuli may be important for the chronopharmacological effects of hypnotics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.