Cardiac Hormones Activate ERK 1/2 Kinases in Human Fibroblasts

Two cardiac hormones, vessel dilator and kaliuretic peptide, localize to fibroblasts with immunohistochemistry. Vessel dilator and kaliuretic peptide were investigated in dose-response and time-sequenced experiments for their cell signaling of extracellular signal-regulated kinases 1/2 in human fibroblasts to test the hypothesis that these two cardiovascular hormones contribute to fibroblast proliferation by activating extracellular signal-regulated kinases 1/2. Vessel dilator at 10 pM (physiological range) enhanced the phosphorylation of extracellular signal-regulated kinases 1/2 by 188+/-9% (p<0.001) in 10 min and, maximally, by 200+/-10% in 15 min (p<0.001). Vessel dilator at 10 nM enhanced the phosphorylation of extracellular signal-regulated kinases 1/2 by 107+/-5% (p<0.01) in 10 min. Kaliuretic peptide at 10 pM enhanced the activation of extracellular signal-regulated kinases 1/2 by 389+/-19% in 10 min (p<0.001). Kaliuretic peptide at 10 nM enhanced the phosphorylation of extracellular signal-regulated kinases 1/2 by 82+/-4% (p<0.01). Our results show that both cardiac hormones activate extracellular signal-regulated kinases 1/2 in human fibroblasts, suggesting that they may have a role in enhancing fibroblast proliferation.