Cardiac up-regulation of NBCe1 emerges as a beneficial consequence of voluntary wheel running in mice

MEDINA, ANDRÉS J.; IBÁÑEZ, ALEJANDRO M.; DIAZ-ZEGARRA, LEANDRO A.; PORTIANSKY, ENRIQUE L.; BLANCO, PAULA G.; PEREYRA, ERICA V.; DE GIUSTI, VERÓNICA C.; AIELLO, ERNESTO A.; YEVES, ALEJANDRA M.; ENNIS, IRENE L.

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS

ELSEVIER SCIENCE INC

Año: 2020 vol. 694

0003-9861

Physicaltraining stimulates the development of physiologic cardiac hypertrophy (CH),being a key event in this process the inhibition of the Na+/H+exchanger. However, the role of the sodium bicarbonate cotransporter (NBC) hasnot been explored yet under this circumstance. C57/Bl6 mice were allowed tovoluntary exercise (wheel running) for five weeks. Cardiac mass was evaluatedby echocardiography and histomorphometry detecting that training promoted thedevelopment of physiological CH (heart weight/tibia length ratio, mg/mm:6.54±0.20 vs 8.81±0.24; interstitial collagen content, %: 3.14±0.63 vs.1.57±0.27; and cross-sectional area of cardiomyocytes, µm2:200.6±8.92 vs. 281.9±24.05; sedentary (Sed) and exercised (Ex) mice,respectively). The activity of the electrogenic isoform of the cardiac NBC(NBCe1) was estimated by recording intracellular pH under high potassiumconcentration and by measuring action potential duration (APD). NBCe1 activitywas significantly increased in isolated cardiomyocytes of trained mice. Additionally,the APD was shorter and the alkalization due to high extracellularpotassium-induced depolarization was greater in this group, indicating that theNBCe1 was hyperactive. These results are online with the observed myocardialup-regulation of the NBCe1 (Western Blot, %: 100±13.86 vs. 202±29.98; Sed vs.Ex, n=6 each group). In addition, we detected a reduction in H2O2production in the myocardium of trained mice.Theseresults support that voluntary training induces the development of physiologic CHwith up-regulation of the cardiac NBCe1 in mice. Furthermore, the improvementin the antioxidant capacity contributes to the beneficial cardiovascularconsequences of physical training.