期刊
INTERNATIONAL JOURNAL OF CARDIOLOGY
卷 264, 期 -, 页码 137-144出版社
ELSEVIER IRELAND LTD
DOI: 10.1016/j.ijcard.2018.03.066
关键词
Angiotensin-(1-12); Chymase; Heart failure; Cardiomyocyte; Contractility; Calcium transient
资金
- National Institutes of Health [R01AG049770, P01HL051952-21, R01HL074318]
- National Natural Science Foundation of China [81270252]
Background: Angiotensin-(1-12) [Ang-(1-12)] is a chymase-dependent source for angiotensin II (Ang II) cardiac activity. The direct contractile effects of Ang-(1-12) in normal and heart failure (HF) remain to be demonstrated. We assessed the hypothesis that Ang-(1-12) may modulate [Ca2+](i) regulation and alter cardiomyocyte contractility in normal and HF rats. Methods and results: We compared left ventricle (LV) myocyte contractile and calcium transient ([Ca2+](iT)) responses to angiotensin peptides in 16 SD rats with isoproterenol-induced HF and 16 age-matched controls. In normal myocytes, versus baseline, Ang II (10(-6) M) superfusion significantly increased myocyte contractility (dL/dt(max): 40%) and [Ca2+](iT) (29%). Ang-(1-12) (4 x 10(-6) M) caused similar increases in dL/dt(max) (34%) and [Ca2+](iT) (25%). Compared with normal myocytes, superfusion of Ang II and Ang-(1-12) in myocytes obtained from rats with isoproterenol-induced HF caused similar but significantly attenuated positive inotropic actions with about 42% to 50% less increases in dL/dt(max) and [Ca2+](iT). Chymostatin abolished Ang-(1-12)-mediated effects in normal and HF myocytes. The presence of an inhibitory cAMP analog, Rp-cAMPS prevented Ang-(1-12)-induced inotropic effects in both normal and HF myocytes. Incubation of HF myocytes with pertussis toxin (PTX) further augmented Ang II-mediated contractility. Conclusions: Ang-(1-12) stimulates cardiomyocyte contractile function and [Ca2+](iT) in both normal and HF rats through a chymase mediated action. Altered inotropic responses to Ang-(1-12) and Ang II in HF myocytes are mediated through a cAMP-dependent mechanism that is coupled to both stimulatory G and inhibitory PTX-sensitive G proteins. (C) 2018 Elsevier B.V. All rights reserved.
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