AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 2 590-R595, Copyright © 1994 by American Physiological Society
Anoxia and adenosine induce increased cerebral blood flow rate in crucian carp
G. E. Nilsson, P. Hylland and C. O. Lofman
Department of Limnology, Uppsala University, Sweden.
The crucian carp (Carassius carassius) has the rare ability to survive
prolonged anoxia, indicating an extraordinary capacity for glycolytic ATP
production, especially in a highly energy-consuming organ like the brain.
For the brain to be able to increase its glycolytic flux during anoxia and
profit from the large liver glycogen store, an increased glucose delivery
from the blood would be expected. Nevertheless, the effect of anoxia on
brain blood flow in crucian carp has never been studied previously. We have
used epireflection microscopy to directly observe and measure blood flow
rate on the brain surface (optic lobes) during normoxia and anoxia in
crucian carp. We have also examined the possibility that adenosine
participates in the regulation of brain blood flow rate in crucian carp.
The results showed a 2.16-fold increase in brain blood flow rate during
anoxia. A similar increase was seen after topical application of adenosine
during normoxia, while adenosine was without effect during anoxia.
Moreover, superfusing the brain with the adenosine receptor blocker
aminophylline inhibited the effect of anoxia on brain blood flow rate,
clearly suggesting a mediatory role of adenosine in the anoxia-induced
increase in brain blood flow rate.
