Acute myocardial glucocorticoid receptor activation decreases NHE1 activity

AMARILLO ME; PÉREZ NG; PRIETO DÍAZ JP; BARBIERI C ; DÍAZ RG

Rosario

Congreso; Reunión Científica 2019 de la Sociedad Argentina de Fisiología (SAFIS); 2019

Sociedad Argentina de Fisiología (SAFIS)

Background/Aims: Glucocorticoid receptor (GR) is highly expressed on cardiac tissue, but its specific activity remains rather unknown. GR activation following an ischemic insult ameliorates cardiac function through a mechanism that involves calcineurin pathway inactivation. Since cardiac NHE1 activation has been linked to an increased calcineurin activity, we sought to determine if acute GR activation could modulate NHE1 activity.Methods: Experiments were performed in isolated rat papillary muscles. NHE1 activity was assessed by Na+-dependent pHi recovery after acute transient acidosis (ATA). AKT and NHE1 phosphorylation, NHE1 expression and dimerization were determined by western blot.Hydrocortisone (HC) was used to trigger GR activation. Experimental groups: Non-acidotic control, ATA, ATA+HC 1nM, and ATA+HC 10nM.Results: HC promoted a dose-dependent decrease in NHE1 activity after ATA (JH+: 1.22±0.19 ATA, n=5; vs. 0.68±0.11 HC1, n=4; vs. 0.56±0.15 HC10, n=4, p