Angiotensin-(1–12)/chymase axis modulates cardiomyocyte L-type calcium currents in rats expressing human angiotensinogen

• Published in: International journal of cardiology 2019-12, Vol.297, p.104-110
• Main Authors: Reyes, Santiago, Cheng, Che Ping, Roberts, Drew J., Yamashita, Tomohisa, Ahmad, Sarfaraz, VonCannon, Jessica L., Wright, Kendra N., Dell’Italia, Louis J., Varagic, Jasmina, Ferrario, Carlos M.
• Format: Article
• Language: English
• Subjects: Ang II; Ang-(1–12); Angiotensin I - metabolism; Angiotensin II type 1 receptor; Angiotensinogen - metabolism; Animals; Calcium Channels, L-Type - metabolism; Cell Culture Techniques; Chymase; Chymases - metabolism; Hypertension; Hypertrophy; Myocytes, Cardiac - metabolism; Patch-Clamp Techniques; Peptide Fragments - metabolism; Rats; Rats, Sprague-Dawley; Rats, Transgenic
• ISSN: 0167-5273; 1874-1754; 1874-1754
• DOI: 10.1016/j.ijcard.2019.09.052

Activation of the intracrine renin angiotensin systems (RAS) is increasingly recognized as contributing to human pathologies, yet non-canonical renin-independent mechanisms for angiotensin II (Ang II) biosynthesis remain controversial. Direct Ang II generation from angiotensin-(1–12) [Ang-(1–12)] by chymase is an essential intracrine source for regulation of cardiac function. Using a transgenic rat model that overexpresses the human angiotensinogen gene [TGR(hAGT)L1623] and displays increased cardiac Ang II levels, this study aimed to provide evidence for intracrine activation of L-type calcium currents (ICa-L) mediated by the Ang-(1–12)/chymase axis. On patch clamp, ICa-L density was significantly higher in TGR(hAGT)L1623 (−6.4 ± 0.3 pA/pF) compared to Sprague Dawley (SD) cardiomyocytes (−4.8, ± 0.5 pA/pF). Intracellular administration of Ang II and Ang-(1–12) elicited a ICa-L increase in both SD and TGR(hAGT)L1623 cardiomyocytes, albeit blunted in transgenic cells. ICa-L activation by intracellular Ang II and Ang-(1–12) was abolished by the specific Ang II type 1 receptor blocker E−3174. Co-administration of a chymase inhibitor prevented activation of ICa-L by Ang-(1–12). Confocal micrographs revealed abundant chymase (mast cell protease 5) immunoreactive protein in SD and TGR(hAGT)L1623 cardiomyocytes. Our data demonstrate the existence in cardiomyocytes of a calcium channel modulatory activity responsive to Ang II generated by the Ang-(1–12)/chymase axis that signals via intracellular receptors. Chronically elevated Ang II in TGR(hAGT)L1623 hearts leading to increased intracellular calcium through ICa-L suggests that activation of this Ang-(1–12)/chymase-governed cardiac intracrine RAS may contribute to the pathological phenotypes observed in the humanized model of chronic hypertension and cardiac hypertrophy. •Ang-(1–12)/chymase axis is active in cardiomyocytes of Ang II-mediated heart disease model.•Intracellular Ang II and Ang-(1–12) control L-type calcium currents.•Chymase inhibition prevents Ang-(1–12) L-type calcium channel activation.•Ang II formed by Ang-(1–12)/chymase axis acts via AT1 receptors.•Targeting Ang-(1–12)/chymase axis in cardiac tissue may add benefit to current care.