SERCA overexpression reduces hydroxyl radical injury in murine myocardium.

Hydroxyl radicals (*OH) are involved in the pathogenesis of ischemia-reperfusion injury and are observed in clinical situations, including acute heart failure, stroke, and myocardial infarction. Acute transient exposure to *OH causes an intracellular Ca(2+) overload and leads to impaired contractility. We investigated whether upregulation of sarcoplasmic reticulum Ca(2+)-ATPase function (SERCA) can attenuate *OH-induced dysfunction. Small, contracting right ventricular papillary muscles from wild-type (WT) SERCA1a-overexpressing (transgenic, TG) and SERCA2a heterogeneous knockout (HET) mice were directly exposed to *OH. This brief 2-min exposure led to a transient elevation of diastolic force (F(dia)) and depression of developed force (F(dev)). In WT mice, F(dia) increased to 485 +/- 49% and F(dev) decreased to 11 +/- 3%. In sharp contrast, in TG mice F(dia) increased only to 241 +/- 17%, whereas F(dev) decreased only to 51 +/- 5% (P < 0.05 vs. WT). In HET mice, F(dia) rose more than WT (to 597 +/- 20%, P < 0.05), whereas F(dev) was reduced in a similar amount. After approximately 45 min after *OH exposure, a new steady state was reached: F(dev) returned to 37 +/- 6% and 32 +/- 6%, whereas F(dia) came back to 238 +/- 28% and 292 +/- 17% in WT and HET mice, respectively. In contrast, the sustained dysfunction was significantly less in TG mice: F(dia) and F(dev) returned to 144 +/- 20% and 67 +/- 6%, respectively. Before exposure to *OH, there is decrease in phospholamban (PLB) phosphorylation at Ser16 (pPLBSer16) and PLB phosphorylation at Thr17 (pPLBThr17) in TG mice and an increase in pPLBSer16 and pPLBThr17 in HET mice versus WT. After exposure to *OH there is decrease in pPLBSer16 in WT, TG, and HET mice but no significant change in the level of pPLBThr17 in any group. The results indicate that SERCA overexpression can reduce the *OH-induced contractile dysfunction in murine myocardium, whereas a reduced SR Ca(2+)-ATPase activity aggravates this injury. Loss of pPLB levels at Ser16 likely amplifies the differences observed in injury response.

[1]  P. Janssen,et al.  Effect of muscle dimensions on trabecular contractile performance under physiological conditions , 2006, Pflügers Archiv.

[2]  J. Ross,et al.  Gene transfer of a phospholamban-targeted antibody improves calcium handling and cardiac function in heart failure. , 2005, Cardiovascular research.

[3]  S. Huke,et al.  Altered force-frequency response in non-failing hearts with decreased SERCA pump-level. , 2003, Cardiovascular research.

[4]  G. Hasenfuss,et al.  Hydroxyl Radical-Induced Acute Diastolic Dysfunction Is Due to Calcium Overload via Reverse-Mode Na+-Ca2+ Exchange , 2002, Circulation research.

[5]  Eduardo Marbán,et al.  Myofilament properties comprise the rate-limiting step for cardiac relaxation at body temperature in the rat. , 2002, American journal of physiology. Heart and circulatory physiology.

[6]  E. Marbán,et al.  Sarcoplasmic Reticulum Ca2+ ATPase (SERCA) 1a Structurally Substitutes for SERCA2a in the Cardiac Sarcoplasmic Reticulum and Increases Cardiac Ca2+ Handling Capacity , 2001, Circulation research.

[7]  I. Farrance,et al.  Comparison of SERCA1 and SERCA2a expressed in COS-1 cells and cardiac myocytes. , 1999, American journal of physiology. Heart and circulatory physiology.

[8]  E. Marbán,et al.  Molecular and cellular mechanisms of myocardial stunning. , 1999, Physiological reviews.

[9]  G. Hasenfuss,et al.  Transient and sustained impacts of hydroxyl radicals on sarcoplasmic reticulum function: protective effects of nebivolol. , 1999, European journal of pharmacology.

[10]  T. Doetschman,et al.  Impaired Cardiac Performance in Heterozygous Mice with a Null Mutation in the Sarco(endo)plasmic Reticulum Ca2+-ATPase Isoform 2 (SERCA2) Gene* , 1999, The Journal of Biological Chemistry.

[11]  R. Walsh,et al.  Enhanced myocardial contractility and increased Ca2+ transport function in transgenic hearts expressing the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+-ATPase. , 1998, Circulation research.

[12]  U. Schmidt,et al.  Adenoviral gene transfer of phospholamban in isolated rat cardiomyocytes. Rescue effects by concomitant gene transfer of sarcoplasmic reticulum Ca(2+)-ATPase. , 1997, Circulation research.

[13]  P. D. de Tombe,et al.  Uncontrolled sarcomere shortening increases intracellular Ca2+ transient in rat cardiac trabeculae. , 1997, The American journal of physiology.

[14]  E. Marbán,et al.  Selective effects of oxygen free radicals on excitation-contraction coupling in ventricular muscle. Implications for the mechanism of stunned myocardium. , 1996, Circulation.

[15]  W C Hunter,et al.  Force, not sarcomere length, correlates with prolongation of isosarcometric contraction. , 1995, The American journal of physiology.

[16]  R. Ferrari,et al.  Cardioprotection by nisoldipine: role of timing of administration. , 1993, European heart journal.

[17]  N. Alpert,et al.  Alterations in sarcoplasmic reticulum gene expression in human heart failure. A possible mechanism for alterations in systolic and diastolic properties of the failing myocardium. , 1993, Circulation research.

[18]  W C Hunter,et al.  A method to reconstruct myocardial sarcomere lengths and orientations at transmural sites in beating canine hearts. , 1992, The American journal of physiology.

[19]  T. Ehring,et al.  The Calcium Antagonist Nisoldipine Improves the Functional Recovery of Reperfused Myocardium Only When Given Before Ischemia , 1992, Journal of cardiovascular pharmacology.

[20]  N. Alpert,et al.  Altered Myocardial Force‐Frequency Relation in Human Heart Failure , 1992, Circulation.

[21]  H. Keurs,et al.  Force and velocity of sarcomere shortening in trabeculae from rat heart. Effects of temperature. , 1990 .

[22]  M. Weisfeldt,et al.  Measurement and characterization of postischemic free radical generation in the isolated perfused heart. , 1989, The Journal of biological chemistry.

[23]  N. Alpert,et al.  Protection of Human Left Ventricular Myocardium From Cutting Injury With 2,3 -Butanedione Monoxime , 1989, Circulation research.

[24]  H. E. Keurs,et al.  The force-frequency relationship in rat myocardium , 1986, Pflügers Archiv.

[25]  H. T. ter Keurs,et al.  Tension Development and Sarcomere Length in Rat Cardiac Trabeculae: Evidence of Length‐Dependent Activation , 1980, Circulation research.

[26]  Ron B. H. Wills,et al.  Effects of temperature. , 2007 .

[27]  M. Flesch,et al.  Effect of beta-blockers on free radical-induced cardiac contractile dysfunction. , 1999, Circulation.

[28]  J. Kentish,et al.  Positive force- and [Ca2+]i-frequency relationships in rat ventricular trabeculae at physiological frequencies. , 1999, American journal of physiology. Heart and circulatory physiology.

[29]  M. Periasamy,et al.  SERCA1a can functionally substitute for SERCA2a in the heart. , 1999, American journal of physiology. Heart and circulatory physiology.

[30]  J. Kaszaki,et al.  Toxic oxygen metabolites and ischemia-reperfusion increase histamine synthesis and release in the isolated rat heart. , 1993, Journal of molecular and cellular cardiology.

[31]  K. Boheler,et al.  Altered sarcoplasmic reticulum Ca2(+)-ATPase gene expression in the human ventricle during end-stage heart failure. , 1990, The Journal of clinical investigation.