Esposito G, Perrino C, Ozaki T, Takaoka H, Defer N, Petretta MP, De Angelis MC, Mao L, Hanoune J, Rockman HA, Chiariello M. Increased myocardial contractility and enhanced exercise function in transgenic mice overexpressing either adenylyl cyclase 5 or 8.
Basic Res Cardiol 2007;
103:22-30. [PMID:
18034275 DOI:
10.1007/s00395-007-0688-6]
[Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Accepted: 10/22/2007] [Indexed: 01/08/2023]
Abstract
OBJECTIVE
ss-adrenergic receptors (ssARs) are powerful regulators of cardiac function in vivo, activating heterotrimeric G proteins and the effector molecule adenylyl cyclase (AC). Interestingly, cardiac-specific overexpression of different AC isoforms leads to variable changes in cardiac function. Whether AC overexpression affects intrinsic cardiac contractility in an isoform-specific fashion determining a change in exercise capacity is currently unknown.
METHODS
To address this issue, we performed load-independent measurements of cardiac systolic and diastolic function by pressure-volume (PV) loop analysis in intact wild-type mice (WT) and transgenic mice overexpressing the AC isoforms 5 or 8.
RESULTS
Here we show that cardiac overexpression of either AC5 or AC8 transgenic mice determined an increase in intrinsic cardiac contractility. Interestingly, AC8 transgenic mice displayed a significantly greater increase in cardiac contractility and improved active phase of relaxation. Despite these differences detected by PV loop analysis, both AC5 and AC8 mice showed a marked increase in exercise capacity on treadmill testing.
CONCLUSIONS
Our results demonstrate that load-independent measurements of cardiac function are needed to compare different groups of genetically-modified mouse models and to detect subtle AC isoform-specific changes in cardiac performance.
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