Mitochondrial respiration and succinate dehydrogenase are suppressed early during entrance into a hibernation bout, but membrane remodeling is only transient.

We examined respiration and lipid composition of liver mitochondria purified from a hibernator (Ictidomys tridecemlineatus) in different stages of a torpor bout. Between interbout euthermia (body temperature, T (b), 37°C) and early entrance (T (b) 30°C), state 3 and state 4 respirations, fueled by 6 mM succinate, fell by over 50%. Mitochondrial respiration did not decline any further in the late entrance and torpor stages (T (b) 15 and 5°C, respectively).