Slow death in the leopard frog Rana pipiens: neurotransmitters and anoxia tolerance.

While frogs such as Rana temporaria are known to withstand 4-5 h anoxia at room temperature, little is known about the neurological adaptations that permit this. Previous research has shown that changes in neuroactive compounds such as glutamate and dopamine in anoxia-sensitive (mammalian) brains follow a strikingly different pattern than is observed in truly anoxia-tolerant vertebrates such as the freshwater turtle. The present study measured changes in the levels of whole brain and extracellular amino acids, and extracellular dopamine, in the normoxic and 3-4 h anoxic frog Rana pipiens, in order to determine whether their neurotransmitter responses resemble the anoxia-vulnerable or anoxia-tolerant response.