Cardiomyocytes
Cardiomyocyte MR plays a role in regulating cardiac function, electrical
conduction and fibrosis, through direct signal mediation and through
paracrine MR-dependent activity. In neonatal rat cardiomyocytes,
aldosterone induces expression of angiotensin-converting enzyme via MR,
creating a vicious circular cascade involving the
renin-angiotensin-aldosterone-system (Harada et al., 2001). Long-time
aldosterone exposure induces cardiomyocyte hypertrophy, this effect
being suppressed by eplerenone (Yamamuro et al., 2006). Moreover, MR
activation by aldosterone led to an increase in the hypertrophic and
pro-inflammatory cytokine cardiotrophin-1 (CT-1) in adult HL-1
cardiomyocytes, suggesting CT-1 as a possible mediator of cardiomyocyte
growth (López-Andrés et al., 2008). Finally, CD14, a ligand of TLR4
(toll-like receptor-4), has been proposed as a mediator of the
chronotropic effects of the aldosterone/MR pathway activation in
cardiomyocytes (Mannic et al., 2015). Thus, MR activation plays a
central role in cardiomyocyte hypertrophy.