High-dose chloroquine is metabolically cardiotoxic by inducing lysosomes and mitochondria dysfunction in a rat model of pressure overload hypertrophy.

Autophagy, macroautophagy and chaperone-mediated autophagy (CMA), are upregulated in pressure overload (PO) hypertrophy. In this study, we targeted this process at its induction using 3 methyladenine and at the lysosomal level using chloroquine and evaluated the effects of these modulations on cardiac function and myocyte ultrastructure. Sprague-Dawley rats weighing 200 g were subjected to ascending aortic banding. After 1 week of PO, animals were randomized to receive 3 methyladenine versus chloroquine, intraperitoneally, for 2 weeks at a dose of 40 and 50 mg/kg/day, respectively. Saline injection was used as control. Chloroquine treatment, in PO, resulted in regression in cardiac hypertrophy but with significant impairments in cardiac relaxation and contractility. Ultrastructurally, chloroquine accentuated mitochondrial fragmentation and cristae destruction with a plethora of autophagosomes containing collapsed mitochondria and lysosomal lamellar bodies. In contrast, 3 methyladenine improved cardiac function and attenuated mitochondrial fragmentation and autophagososme formation. Markers of macroautophagy and CMA were significantly decreased in the chloroquine group; whereas 3 methyladenine treatment significantly attenuated macroautophagy with a compensatory increase in CMA. Furthermore, chloroquine accentuated PO induced oxidative stress through the further decrease in the expression of manganese superoxide dismutase; whereas, 3 MA had a completely opposite effect. Taken together, these data suggest that high-dose chloroquine, in addition to its effect on the autophagy-lysosome pathway, significantly impairs mitochondrial antioxidant buffering capacity and accentuates oxidative stress and mitochondrial dysfunction in PO hypertrophy; highlighting, the cautious administration of this drug in high oxidative stress conditions, such as pathological hypertrophy or heart failure.