TISSUE-SPECIFIC CHANGES IN PROTEIN-SYNTHESIS RATES IN-VIVO DURING ANOXIA IN CRUCIAN CARP

Mechanisms of anoxia tolerance were investigated in crucian carp. Rate s of protein synthesis were calculated in selected tissues of normoxic and anoxic animals. Exposure to 48 h of anoxia resulted in a signific ant reduction in protein synthesis in the liver (>95%), heart (53%), a nd red and white muscle (52 and 56%, respectively), whereas brain prot ein synthesis rates were unaffected. Seven days of anoxia produced sim ilar results. After 24 h of recovery from a 48-h anoxic period, protei n synthesis rates had virtually returned to normoxic values. The effec t of anoxia on the amount of RNA (relative to protein) varied dependin g on the tissue and also the length of exposure (except in the brain, where it was consistently reduced). However, the effect on RNA transla tional efficiency was purely tissue specific (i.e., independent of exp osure time) and was unaffected in the heart, reduced in the liver and red and white muscle, and increased in the brain. Downregulation of pr otein synthesis on a tissue-specific basis appears to be a significant mechanism for energy conservation as well as maintaining neural funct ion, thus promoting survival during anoxia.