The phospholipid and protein compositions of mitochondrial membranes from 
hepatopancreas of active and estivating terrestrial snails (Cepaea nemoralis) 
were compared. Mitochondria from estivating snails contained 82.7% less 
cardiolipin, and this was associated with an 83.9% reduction in cytochrome-c 
oxidase activity. Substantial changes also occurred in the proportional amounts 
of other individual phospholipid classes and their constituent fatty acids, 
including a 72% loss of total mitochondrial phospholipids, a 37% increase in 
monoenes, and 49% fewer n-3 fatty acids in membranes of estivating snails. These 
changes are consistent with those correlated with lowered metabolic rate and 
lower rates of proton leak in other animal models. Estivating snail 
hepatopancreas showed no change in total phospholipid content, indicating that 
the phospholipids lost from mitochondrial membranes may be sequestered elsewhere 
within the cell. We suggest that estivating snails remodel mitochondrial 
membranes as part of a coordinated, reversible suppression of mitochondrial 
membrane-associated processes, which may include a concomitant reduction in 
rates of proton pumping and leaking.