BOUTILIER, Robert G.; University of Cambridge: Mechanisms of metabolic rate depression in overwintering ectotherms.

In an influential Science article⁽¹⁾ in 1986, Peter Hochachka pointed out that most animals experience some degree of hypoxia and hypothermia during the course of their natural life history either as a consequence of ambient ‘exposure’ per se, or through metabolic, respiratory and/or circulatory insufficiency. An experimental approach that he subsequently championed was to probe tissues from natural models of hypoxia-tolerant and cold-tolerant vertebrates to look for common mechanisms of defense against O₂-lack and hypothermia. Indeed, his early insights predicted that numerous hibernating endotherms, neonatal and diving mammals, as well as many ectotherms would tolerate prolonged periods that would in clinical terms be called asphyxia or deep hypothermia. He reasoned that the single most protective and unifying feature of cold-tolerance in hibernating and neonatal mammals is the same one that ensures their enhanced survival in O₂-limiting conditions; a regulated metabolic depression. Our studies on hibernating frogs have been guided by his concept of �metabolic arrest� which we interpret as an integrated central defense mechanism operating at cellular, systemic and whole animal levels. (1). Hochachka, P. W. (1986). Defense strategies against hypoxia and hypothermia. Science 231, 234�241.