Hypoxia stimulates cerebral blood flow in the estuarine crocodile (Crocodylus porosus)

Neurosci Lett. 1999 May 21;267(1):1-4. doi: 10.1016/s0304-3940(99)00269-4.


The effect of N2 respiration on cerebral blood flow (CBF) velocity on the dorsal surface of cerebellum was examined in the estuarine crocodile, Crocodylus porosus, using epi-illumination microscopy. Twelve minutes of N2 respiration resulted in a 126% increase in CBF velocity. N2 respiration had no effect on blood pressure, indicating an underlying cerebral vasodilation. In addition, heart rate increased significantly. Systemic injections of aminophylline and the NO synthase (NOS) inhibitor nitro-L-arginine (L-NA) did not affect the hypoxia induced increase in CBF. We conclude that C. porosus responds to hypoxia with adenosine and nitric oxide (NO) independent cerebral vasodilation, and that this is likely to be a mechanism protecting the brain from energy deficiency during prolonged dives.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alligators and Crocodiles
  • Aminophylline / pharmacology
  • Animals
  • Blood Flow Velocity
  • Cerebrovascular Circulation / physiology*
  • Enzyme Inhibitors / pharmacology
  • Hypoxia, Brain / metabolism
  • Hypoxia, Brain / physiopathology*
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase / metabolism
  • Nitroarginine / pharmacology
  • Vasodilation


  • Enzyme Inhibitors
  • Nitroarginine
  • Aminophylline
  • Nitric Oxide
  • Nitric Oxide Synthase