1. Aging related functional and structural changes in the heart and aorta: MitoTEMPO improves aged-cardiovascular performance
- Author
-
Sinan Degirmenci, Aysegul Durak, Yusuf Olgar, Belma Turan, Gizem Kayki-Mutlu, Deniz Billur, Ebru Arioglu-Inan E, and Belgin Can
- Subjects
Male ,0301 basic medicine ,Aging ,medicine.medical_specialty ,Mean arterial pressure ,Myofilament ,Contraction (grammar) ,030204 cardiovascular system & hematology ,Mitochondrion ,medicine.disease_cause ,Biochemistry ,Antioxidants ,Muscle hypertrophy ,03 medical and health sciences ,Organophosphorus Compounds ,0302 clinical medicine ,Endocrinology ,Piperidines ,Internal medicine ,medicine.artery ,Heart rate ,Genetics ,medicine ,Animals ,Myocytes, Cardiac ,Rats, Wistar ,Molecular Biology ,Aorta ,Chemistry ,Cell Biology ,Glucose Tolerance Test ,Mitochondria ,Rats ,Oxidative Stress ,030104 developmental biology ,Insulin Resistance ,Reactive Oxygen Species ,Oxidative stress - Abstract
Aging in humans represents declining in cardio-protective systems, however its mechanisms are not known yet. We aimed to analyse how aging affects key mechanisms responsible for contractile dysfunction via comparing the improperly synchrony between electrical and mechanical activities in male aged-rats (24-month old) comparison to those of adult-rats (6-month old). We determined significantly increased systemic oxidative stress with decreased antioxidant capacity, clear insulin resistance and hypertrophy in aged-rats with normal fasting blood glucose. We also determined significantly high level of reactive oxygen species, ROS production in fluorescent dye chloromethyl-2′,7′-dichlorodihydrofluoroscein diacetate (DCFDA) loaded isolated cardiomyocytes from aged-rats, confirming the increased oxidative stress in these hearts. In situ electrocardiograms, ECGs presented significant prolongations in RR- and QT-intervals in the aged-rats. Invasive hemodynamic measurements demonstrated marked increases in the heart rate and mean arterial pressure and decreases in the ejection-fraction and preload-recruitable stroke-work, together with depressed contraction and relaxation activities in aortic rings. In light and electron microscopy examinations in aged-rats, significant increases in muscle fibre radius and amount of collagen fibres were detected in the heart as well as markedly flattened and partial local splitting in elastic lamellas in the aorta, besides irregularly clustered mitochondria and lysosomes around the myofilaments in cardiomyocytes. MitoTEMPO treatment of tissue samples and cardiomyocytes from aged-rats for 1-h induced significant structural improvements. In the second part of our study, we have shown that mitochondria-targeted antioxidant MitoTEMPO antagonized all alterations in the heart samples as well as penylephrine-induced contractile and acetylcholine-induced relaxation responses of aged-rat aortic rings. Overall, the present data strongly support the important role of mitochondrial oxidative stress in the development of aged-related insufficiencies and that antioxidant strategies specifically targeting this organelle could have therapeutic benefit in aging-associated complications.
- Published
- 2018
- Full Text
- View/download PDF