Regional spinal cord blood flow during sleep-waking cycle in rabbit.

Spinal cord blood flow (SCBF) was measured in rabbits during the sleep-waking cycle with the use of radioactive microspheres. The values obtained during wakefulness (W), synchronized sleep (SS), and desynchronized sleep (DS) were 18.1 +/- 2.1, 18.9 +/- 2.6, and 34.4 +/- 2.5 (SE) ml X min-1 X 100 g-1, respectively. Differences relative to SS were not significant in W and were significant at the 0.05 level in DS (modified t test and Bonferroni's method). The increase in blood flow during DS was due to a decrease in vascular resistance. The mechanism of the vasodilation during DS has yet to be identified.