Skip to main content
NCBI home page
The Journal of Clinical Investigation logoLink to The Journal of Clinical Investigation
. 1996 Apr 1;97(7):1618–1623. doi: 10.1172/JCI118587

Enhanced myocardial relaxation in vivo in transgenic mice overexpressing the beta2-adrenergic receptor is associated with reduced phospholamban protein.

H A Rockman 1, R A Hamilton 1, L R Jones 1, C A Milano 1, L Mao 1, R J Lefkowitz 1
PMCID: PMC507225  PMID: 8601626

Abstract

To assess the effect of targeted myocardial beta-adrenergic receptor (AR) stimulation on relaxation and phospholamban regulation, we studied the physiological and biochemical alterations associated with overexpression of the human beta2-AR gene in transgenic mice. These mice have an approximately 200-fold increase in beta-AR density and a 2-fold increase in basal adenylyl cyclase activity relative to negative littermate controls. Mice were catheterized with a high fidelity micromanometer and hemodynamic recordings were obtained in vivo. Overexpression of the beta2-AR altered parameters of relaxation. At baseline, LV dP/dt(min) and the time constant of LV pressure isovolumic decay (Tau) in the transgenic mice were significantly shorter compared with controls, indicating markedly enhanced myocardial relaxation. Isoproterenol stimulation resulted in shortening of relaxation velocity in control mice but not in the transgenic mice, indicating maximal relaxation in these animals. Immunoblotting analysis revealed a selective decrease in the amount of phospholamban protein, without a significant change in the content for either sarcoplasmic reticulum Ca2+ ATPase or calsequestrin, in the transgenic hearts compared with controls. This study indicates that myocardial relaxation is both markedly enhanced and maximal in these mice and that conditions associated with chronic beta-AR stimulation can result in a selective reduction of phospholamban protein.

Full Text

The Full Text of this article is available as a PDF (223.0 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Arai M., Alpert N. R., MacLennan D. H., Barton P., Periasamy M. Alterations in sarcoplasmic reticulum gene expression in human heart failure. A possible mechanism for alterations in systolic and diastolic properties of the failing myocardium. Circ Res. 1993 Feb;72(2):463–469. doi: 10.1161/01.res.72.2.463. [DOI] [PubMed] [Google Scholar]
  2. Benjamin I. J., Jalil J. E., Tan L. B., Cho K., Weber K. T., Clark W. A. Isoproterenol-induced myocardial fibrosis in relation to myocyte necrosis. Circ Res. 1989 Sep;65(3):657–670. doi: 10.1161/01.res.65.3.657. [DOI] [PubMed] [Google Scholar]
  3. Blaustein A. S., Gaasch W. H. Myocardial relaxation. VI. Effects of beta-adrenergic tone and asynchrony on LV relaxation rate. Am J Physiol. 1983 Mar;244(3):H417–H422. doi: 10.1152/ajpheart.1983.244.3.H417. [DOI] [PubMed] [Google Scholar]
  4. Böhm M., Reiger B., Schwinger R. H., Erdmann E. cAMP concentrations, cAMP dependent protein kinase activity, and phospholamban in non-failing and failing myocardium. Cardiovasc Res. 1994 Nov;28(11):1713–1719. doi: 10.1093/cvr/28.11.1713. [DOI] [PubMed] [Google Scholar]
  5. Cohn J. N., Levine T. B., Olivari M. T., Garberg V., Lura D., Francis G. S., Simon A. B., Rector T. Plasma norepinephrine as a guide to prognosis in patients with chronic congestive heart failure. N Engl J Med. 1984 Sep 27;311(13):819–823. doi: 10.1056/NEJM198409273111303. [DOI] [PubMed] [Google Scholar]
  6. DePamphilis M. L. Origins of DNA replication in metazoan chromosomes. J Biol Chem. 1993 Jan 5;268(1):1–4. [PubMed] [Google Scholar]
  7. Endoh M., Blinks J. R. Actions of sympathomimetic amines on the Ca2+ transients and contractions of rabbit myocardium: reciprocal changes in myofibrillar responsiveness to Ca2+ mediated through alpha- and beta-adrenoceptors. Circ Res. 1988 Feb;62(2):247–265. doi: 10.1161/01.res.62.2.247. [DOI] [PubMed] [Google Scholar]
  8. Feldman A. M., Ray P. E., Silan C. M., Mercer J. A., Minobe W., Bristow M. R. Selective gene expression in failing human heart. Quantification of steady-state levels of messenger RNA in endomyocardial biopsies using the polymerase chain reaction. Circulation. 1991 Jun;83(6):1866–1872. doi: 10.1161/01.cir.83.6.1866. [DOI] [PubMed] [Google Scholar]
  9. Feldman A. M., Weinberg E. O., Ray P. E., Lorell B. H. Selective changes in cardiac gene expression during compensated hypertrophy and the transition to cardiac decompensation in rats with chronic aortic banding. Circ Res. 1993 Jul;73(1):184–192. doi: 10.1161/01.res.73.1.184. [DOI] [PubMed] [Google Scholar]
  10. Hoit B. D., Khoury S. F., Kranias E. G., Ball N., Walsh R. A. In vivo echocardiographic detection of enhanced left ventricular function in gene-targeted mice with phospholamban deficiency. Circ Res. 1995 Sep;77(3):632–637. doi: 10.1161/01.res.77.3.632. [DOI] [PubMed] [Google Scholar]
  11. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  12. Lindemann J. P., Jones L. R., Hathaway D. R., Henry B. G., Watanabe A. M. beta-Adrenergic stimulation of phospholamban phosphorylation and Ca2+-ATPase activity in guinea pig ventricles. J Biol Chem. 1983 Jan 10;258(1):464–471. [PubMed] [Google Scholar]
  13. Long C. S., Hartogensis W. E., Simpson P. C. Beta-adrenergic stimulation of cardiac non-myocytes augments the growth-promoting activity of non-myocyte conditioned medium. J Mol Cell Cardiol. 1993 Aug;25(8):915–925. doi: 10.1006/jmcc.1993.1104. [DOI] [PubMed] [Google Scholar]
  14. Long C. S., Kariya K., Karns L., Simpson P. C. Sympathetic modulation of the cardiac myocyte phenotype: studies with a cell-culture model of myocardial hypertrophy. Basic Res Cardiol. 1992;87 (Suppl 2):19–31. doi: 10.1007/978-3-642-72477-0_3. [DOI] [PubMed] [Google Scholar]
  15. Luo W., Grupp I. L., Harrer J., Ponniah S., Grupp G., Duffy J. J., Doetschman T., Kranias E. G. Targeted ablation of the phospholamban gene is associated with markedly enhanced myocardial contractility and loss of beta-agonist stimulation. Circ Res. 1994 Sep;75(3):401–409. doi: 10.1161/01.res.75.3.401. [DOI] [PubMed] [Google Scholar]
  16. Milano C. A., Allen L. F., Rockman H. A., Dolber P. C., McMinn T. R., Chien K. R., Johnson T. D., Bond R. A., Lefkowitz R. J. Enhanced myocardial function in transgenic mice overexpressing the beta 2-adrenergic receptor. Science. 1994 Apr 22;264(5158):582–586. doi: 10.1126/science.8160017. [DOI] [PubMed] [Google Scholar]
  17. Movsesian M. A., Karimi M., Green K., Jones L. R. Ca(2+)-transporting ATPase, phospholamban, and calsequestrin levels in nonfailing and failing human myocardium. Circulation. 1994 Aug;90(2):653–657. doi: 10.1161/01.cir.90.2.653. [DOI] [PubMed] [Google Scholar]
  18. Porzio M. A., Pearson A. M. Improved resolution of myofibrillar proteins with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Biochim Biophys Acta. 1977 Jan 25;490(1):27–34. doi: 10.1016/0005-2795(77)90102-7. [DOI] [PubMed] [Google Scholar]
  19. Rockman H. A., Ono S., Ross R. S., Jones L. R., Karimi M., Bhargava V., Ross J., Jr, Chien K. R. Molecular and physiological alterations in murine ventricular dysfunction. Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2694–2698. doi: 10.1073/pnas.91.7.2694. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Rockman H. A., Wachhorst S. P., Mao L., Ross J., Jr ANG II receptor blockade prevents ventricular hypertrophy and ANF gene expression with pressure overload in mice. Am J Physiol. 1994 Jun;266(6 Pt 2):H2468–H2475. doi: 10.1152/ajpheart.1994.266.6.H2468. [DOI] [PubMed] [Google Scholar]
  21. Sham J. S., Jones L. R., Morad M. Phospholamban mediates the beta-adrenergic-enhanced Ca2+ uptake in mammalian ventricular myocytes. Am J Physiol. 1991 Oct;261(4 Pt 2):H1344–H1349. doi: 10.1152/ajpheart.1991.261.4.H1344. [DOI] [PubMed] [Google Scholar]
  22. Solaro R. J., Moir A. J., Perry S. V. Phosphorylation of troponin I and the inotropic effect of adrenaline in the perfused rabbit heart. Nature. 1976 Aug 12;262(5569):615–617. doi: 10.1038/262615a0. [DOI] [PubMed] [Google Scholar]
  23. Ungerer M., Parruti G., Böhm M., Puzicha M., DeBlasi A., Erdmann E., Lohse M. J. Expression of beta-arrestins and beta-adrenergic receptor kinases in the failing human heart. Circ Res. 1994 Feb;74(2):206–213. doi: 10.1161/01.res.74.2.206. [DOI] [PubMed] [Google Scholar]
  24. Varma S. K., Owen R. M., Smucker M. L., Feldman M. D. Is tau a preload-independent measure of isovolumetric relaxation? Circulation. 1989 Dec;80(6):1757–1765. doi: 10.1161/01.cir.80.6.1757. [DOI] [PubMed] [Google Scholar]
  25. Wegener A. D., Jones L. R. Phosphorylation-induced mobility shift in phospholamban in sodium dodecyl sulfate-polyacrylamide gels. Evidence for a protein structure consisting of multiple identical phosphorylatable subunits. J Biol Chem. 1984 Feb 10;259(3):1834–1841. [PubMed] [Google Scholar]
  26. Wegener A. D., Simmerman H. K., Lindemann J. P., Jones L. R. Phospholamban phosphorylation in intact ventricles. Phosphorylation of serine 16 and threonine 17 in response to beta-adrenergic stimulation. J Biol Chem. 1989 Jul 5;264(19):11468–11474. [PubMed] [Google Scholar]
  27. Weisfeldt M. L., Frederiksen J. W., Yin F. C., Weiss J. L. Evidence of incomplete left ventricular relaxation in the dog: prediction from the time constant for isovolumic pressure fall. J Clin Invest. 1978 Dec;62(6):1296–1302. doi: 10.1172/JCI109250. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Xiao R. P., Hohl C., Altschuld R., Jones L., Livingston B., Ziman B., Tantini B., Lakatta E. G. Beta 2-adrenergic receptor-stimulated increase in cAMP in rat heart cells is not coupled to changes in Ca2+ dynamics, contractility, or phospholamban phosphorylation. J Biol Chem. 1994 Jul 22;269(29):19151–19156. [PubMed] [Google Scholar]
  29. Xiao R. P., Lakatta E. G. Beta 1-adrenoceptor stimulation and beta 2-adrenoceptor stimulation differ in their effects on contraction, cytosolic Ca2+, and Ca2+ current in single rat ventricular cells. Circ Res. 1993 Aug;73(2):286–300. doi: 10.1161/01.res.73.2.286. [DOI] [PubMed] [Google Scholar]
  30. Yellin E. L., Hori M., Yoran C., Sonnenblick E. H., Gabbay S., Frater R. W. Left ventricular relaxation in the filling and nonfilling intact canine heart. Am J Physiol. 1986 Apr;250(4 Pt 2):H620–H629. doi: 10.1152/ajpheart.1986.250.4.H620. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Clinical Investigation are provided here courtesy of American Society for Clinical Investigation

RESOURCES