Increased expression of calpain-1 and -2 within cardiac mitochondria and adjacent to the contraction bands in rat myocardium after 14-day cocaine administration: A preliminary study.

Calpains are calcium-dependent proteases implicated in cardiac pathologies that induce mitochondrial dysfunction and intercalated disc disruption. However, their role in cocaine-induced cardiotoxicity remains unclear. This study investigates the effects of subchronic cocaine exposure on cardiac calpain-1 and -2 in vivo. Calpain-1 and -2 expressions specifically increased in the mitochondria and adjacent to contraction bands in the myocardium of rats receiving 14-day cocaine administration (20 mg/kg/day via the tail vein), accompanied by decreased expression of ATP5A1, a subunit of a major component of the mitochondrial respiratory chain, suggesting calpain-related mitochondrial dysfunction. These findings provide preliminary evidence for the calpain involvement in cocaine-induced cardiotoxicity and offer potential insights for characteristic findings at autopsy of cocaine intoxication.