Exercise-induced heart mitochondrial cholesterol depletion influences the inhibition of mitochondrial swelling.

The meaning of cholesterol pool reduction in heart mitochondria after exercise is still unknown phenomenon. Therefore, the aim of the study was to establish whether the decreased cholesterol content in heart mitochondria caused by prolonged swimming may provoke changes in their bioenergetics and affect resistance to calcium chloride-induced mitochondrial swelling. To assess, whether mitochondrial modifications are linked to lipid microdomains disruption, methyl-beta-cyclodextrin (MβCD), a well-known lipid microdomains disrupting agent and cholesterol chelator, was applied to the mitochondria of the control group. Male Wistar rats exercised for 3 hours, burdened with an additional 3 % of their body weight. Their hearts were removed immediately after completing the exercise. Cholesterol depletion, increased membrane fluidity and increased resistance to calcium chloride-induced swelling were observed in post-exercise heart crude mitochondria. Similar results were achieved in 2 % MβCD treated control mitochondria. All of the mitochondrial bioenergetics parameters were similar between the groups. Therefore, the disruption of raft-like microdomains appears to be adaptive changes in the rat heart following exercise.