Administration of enalapril started late in life attenuates hypertrophy and oxidative stress burden, increases mitochondrial mass, and modulates mitochondrial quality control signaling in the rat heart

Mitochondrial dysfunction is a relevant mechanism in cardiac aging. Here, we investigated the effects of late-life enalapril administration at a non-antihypertensive dose on mitochondrial genomic stability, oxidative damage, and mitochondrial quality control (MQC) signaling in the hearts of aged rats. The protein expression of selected mediators (i.e., mitochondrial antioxidant enzymes, energy metabolism, mitochondrial biogenesis, dynamics, and autophagy) was measured in old rats randomly assigned to receive enalapril (n = 8) or placebo (n = 8) from 24 to 27 months of age. We also assessed mitochondrial DNA (mtDNA) content, citrate synthase activity, oxidative lesions to protein and mtDNA (i.e., carbonyls and the abundance of mtDNA 4834 deletion), and the mitochondrial transcription factor A (TFAM) binding to specific mtDNA regions. Enalapril attenuated cardiac hypertrophy and oxidative stress-derived damage (mtDNA oxidation, mtDNA 4834 deletion, and protein carbonylation), while increasing mitochondrial antioxidant defenses. The binding of mitochondrial transcription factor A to mtDNA regions involved in replication and deletion generation was enhanced following enalapril administration. Increased mitochondrial mass as well as mitochondriogenesis and autophagy signaling were found in enalapril-treated rats. Late-life enalapril administration mitigates age-dependent cardiac hypertrophy and oxidative damage, while increasing mitochondrial mass and modulating MQC signaling. Further analyses are needed to conclusively establish whether enalapril may offer cardioprotection during aging.