Limited functional and metabolic improvements in hypertrophic and healthy rat heart overexpressing the skeletal muscle isoform of SERCA1 by adenoviral gene transfer in vivo

Abstract

O'Donnell JM, Fields A, Xu X, Chowdhury SA, Geenen DL, Bi J. Limited functional and metabolic improvements in hypertrophic and healthy rat heart overexpressing the skeletal muscle isoform of SERCA1 by adenoviral gene transfer in vivo. Am J Physiol Heart Circ Physiol 295: H2483-H2494, 2008. First published October 24, 2008 doi:10.1152/ajpheart.01023.2008.-Adenoviral gene transfer of sarco(endo)plasmic reticulum Ca 2ϩ -ATPase (SERCA)2a to the hypertrophic heart in vivo has been consistently reported to lead to enhanced myocardial contractility. It is unknown if the faster skeletal muscle isoform, SERCA1, expressed in the whole heart in early failure, leads to similar improvements and whether metabolic requirements are maintained during an adrenergic challenge. In this study, Ad.cmv.SERCA1 was delivered in vivo to aortic banded and shamoperated Sprague-Dawley rat hearts. The total SERCA content increased 34%. At 48 -72 h posttransfer, echocardiograms were acquired, hearts were excised and retrograded perfused, and hemodynamics were measured parallel to NMR measures of the phosphocreatine (PCr)-to-ATP ratio (PCr/ATP) and energy substrate selection at basal and high workloads (isoproterenol). In the Langendorff mode, the rate-pressure product was enhanced 27% with SERCA1 in hypertrophic hearts and 10% in shams. The adrenergic response to isoproterenol was significantly potentiated in both groups with SERCA1.31 P NMR analysis of PCr/ATP revealed that the ratio remained low in the hypertrophic group with SERCA1 overexpression and was not further compromised with adrenergic challenge.13 C NMR analysis revealed fat and carbohydrate oxidation were unaffected at basal with SERCA1 expression; however, there was a shift from fats to carbohydrates at higher workloads with SERCA1 in both groups. Transport of NADH-reducing equivalents into the mitochondria via the ␣-ketoglutamate-malate transporter was not affected by either SERCA1 overexpression or adrenergic challenge in both groups. Echocardiograms revealed an important distinction between in vivo versus ex vivo data. In contrast to previous SERCA2a studies, the echocardiogram data revealed that SERCA1 expression compromised function (fractional shortening) in the hypertrophic group. Shams were unaffected. While our ex vivo findings support much of the earlier cardiomyocyte and transgenic data, the in vivo data challenge previous reports of improved cardiac function in heart failure models after SERCA intervention. sarco(endo)plasmic reticulum Ca 2ϩ -ATPase; glucose oxidation; fatty acid oxidation; phosphocreatine-to-ATP ratio; myocardial energy potential THE CHANGES in intracellular Ca 2ϩ handling reported for the failing myocardium have been linked to sarco(endo)plasmic reticulum Ca 2ϩ -ATPase (SERCA). Calcium uptake into the sarcoplasmic reticulum (SR) by SERCA determines the rate of calcium removal for relaxation, the SR calcium content, and calcium released for contractions (33,45). In the failing heart, it has been proposed that SERCA contributes to reduced contractil...

Advantages of Catheter-Based Adenoviral Delivery of Genes to the Heart for Studies of Cardiac Disease

“…Surprisingly, we found the overexpression of the SERCA1 isoform actually compromised cardiac performance, in vivo (O'Donnell et al, 2008). Our finding was recently supported by a second report (heart failure model in SERCA2a transgenic mice) (Pinz et al, 2011).…”

“…In support of other reports (Chen et al, 2004;Taluker et al, 2007), we found the strategy significantly improved post-ischemic recovery of cardiac function and metabolism in rat (O'Donnell et al, 2009). However, the strategy compromised cardiac function in the hypertrophic heart (O'Donnell et al, 2008). This finding contradicts the earlier reports which used the conventional catheter-based cross-clamp approach to delivery the cDNA for SERCA2a (Miyamoto et al, 2000;Del Monte et al, 2001;Byrne et al, 2008).…”

“…Therefore, it is important to confirm the relative change in endogenous signal in sham-operated animals and disease models without viral gene transfer. In the case of the aortic-banded pressure-overloaded rat model of cardiac hypertrophy, the change in endogenous LacZ signal is minimal in the heart (O'Donnell et al, 2008). Secondly, the expression of LacZ can be assessed by a colorimetric assay for the increase in blue signal from tissue samples.…”

“…The earlier conventional form of this openchest catheter-based approach has been used extensively to deliver the cDNA for the Ca 2+ -ATPase, SERCA2a, to heart as a potential therapeutic strategy for the treatment of heart failure (Del Monte et al, 2002). While there are a number of reports that this strategy improves cardiac hemodynamics, function, and survival (Miyamoto et al, 2000;Del Monte et al, 2001), the results via our modified approach challenge this data and the safety of the treatment proposed for humans (O'Donnell et al, 2008). Our finding has recently been supported by a second report in transgenic mice overexpressing SERCA2a subjected to ascending aortic constriction (Pinz et al, 2011).…”

“…to the heart and eliminates both virus accumulation and gene transfer to non-target organs in rat (O'Donnell et al, 2004(O'Donnell et al, , 2005(O'Donnell et al, , 2008(O'Donnell et al, , 2009. The earlier conventional form of this openchest catheter-based approach has been used extensively to deliver the cDNA for the Ca 2+ -ATPase, SERCA2a, to heart as a potential therapeutic strategy for the treatment of heart failure (Del Monte et al, 2002).…”