Polyamine and magnesium effects on mitochondrial respiration in control and heat-acclimated rats

Studies were made of polyamine and Mg++ effects on rat liver mitochondrial alpha ketoglutarate oxidase (alphaKGO) and succinoxidase (SO). High spermidine levels suppress S3 and S4 of alphaKGO at 0.6-1.17 mM Mg++: some combinations of it and Mg++ increase the respiratory control ratio (RCR). Spermine suppresses S4 of alphaKGO and increases the RCR but suppresses the RCR of SO at high levels. In heat-acclimated (HA) animals in which we have studied only spermine effects on alphaKGO, RCRs of HA rats are greatly increased compared to those of controls.