Advertisement

Myocardial energetics and diastolic dimensions of the heart in experimental hypertension

  • Peter Friberg
Conference paper

Summary

The present study examined changes in left ventricular design and function in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY), and in SHR exposed to voluntary physical exercise in running wheels (R-SHR) and their respective sedentary controls (C-SHR). End-diastolic volumes were obtained in vitro by determining the pressure-volume relationships of isolated hearts arrested in diastole. Cardiac function and myocardial oxygen consumption were also assessed in vitro by means of an antegrade working heart perfusion technique.

Compared with WKY and C-SHR respectively, ordinary SHR and R-SHR had increased end-diastolic volumes, whereas the ratios between wall thickness and internal radius were relatively unchanged. Maximal cardiac performance was elevated in the structurally enlarged SHR heart compared with WKY, whereas it remained unchanged after chronic physical exercise. Long-term voluntary running in SHR caused an elevation of cardiac output due to an increased stroke volume, while arterial pressure was unaltered.

The stimulus for the cardiac redesign to a structurally enlarged heart can probably best be explained by a chronic elevation in cardiac filling. Hence, enlarged left ventricles can then produce higher stroke volumes for given degrees of myocardial fibre shortenings. Thus, despite structurally enlarged left ventricles in SHR and in R-SHR and also increased arterial pressure in SHR compared with WKY (thereby elevating systolic wall stress), cardiac function was maintained and even augmented, which was not associated with an increase in total myocardial oxygen consumption.

Keywords

Coronary Flow Myocardial Oxygen Consumption Coronary Vascular Resistance Myocardial Energetic Voluntary Running 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Katz R, Karliner JS, Resnik R (1978) Effects of a natural volume overload state (pregnancy) on left ventricular performance in normal human subjects. Circulation 58 (3): 434–441PubMedCrossRefGoogle Scholar
  2. 2.
    Morton M, Tsang H, Hohimer R, Ross R, Thornburg K, Faber J, Metcalfe J (1984) Left ventricular size, output, and structure during guinea pig pregnancy. Am J Physiol 226: R40 — R48Google Scholar
  3. 3.
    Friberg P, Folkow B, Nordlander M (1985) Structural adaptation of the rat left ventricle in response to changes in pressure and volume loads. Acta Physiol Scand 125: 67–79PubMedCrossRefGoogle Scholar
  4. 4.
    Goldman S, Olajos M, Friedman H, Roeske WR, Morkin E (1982) Left ventricular performance in conscious thyrotoxic calves. Am J Physiol 242: H113 — H121PubMedGoogle Scholar
  5. 5.
    Friberg P, Wählander H, Nordlander M (1986) Dimensional and functional behavior of the rat heart exposed to various haemodynamic alterations. J Hypertension 4: S127 — S129Google Scholar
  6. 6.
    Saragoca MA, Tarazi RC (1981) Left ventricular hypertrophy in rats with renovascular hypertension. Alterations in cardiac function and adrenergic responses. Hypertension [Suppl II] 3:11–171—II-196Google Scholar
  7. 7.
    Noresson E, Ricksten S-E, Hallbäck-Nordlander M, Thoren P (1979) Performance of the hypertrophied left ventricle in spotaneously hypertensive rat. Effects of changes in preload and after-load. Acta Physiol Scand 107: 1–8Google Scholar
  8. 8.
    Pfeffer JM, Pfeffer MA, Fishbein MC, Frohlich ED (1979) Cardiac function and morphology with aging in the spontaneously hypertensive rat. Am J Physiol 237 (4): H461 — H468PubMedGoogle Scholar
  9. 9.
    Lundin S, Friberg P, Hallbäck-Nordlander M (1982) Left ventricular hypertrophy improves cardiac performance in spontaneously hypertensive rats. Acta Physiol Scand 114: 321–328PubMedCrossRefGoogle Scholar
  10. 10.
    Friberg P, Nordlander M, Lundin S, Folkow B (1985) Effects of ageing on cardiac performance and coronary flow in spontaneously hypertensive and normotensive rats. Acta Physiol Scand 125: 1–11PubMedCrossRefGoogle Scholar
  11. 11.
    Friberg P, Nordborg C (1986) Functional, morphological and metabolic characteristics of isolated hearts from normotensive and spontaneously hypertensive rats before, during and after renal hypertension. Acta Physiol Scand 126: 161–171PubMedCrossRefGoogle Scholar
  12. 12.
    Shimamatsu K, Fouad-Tarazi F (1986) Basal inotropic state in rats with renal hypertension: influence of coronary flow and perfusion pressure. Cardiovasc Res 20: 269–274PubMedCrossRefGoogle Scholar
  13. 13.
    Scheuer J, Tipton CM (1977) Cardiovascular adaptations to physical training. Ann Rev Physiol 39: 221–251CrossRefGoogle Scholar
  14. 14.
    Pfeffer MA, Ferrell BA, Pfeffer JM, Weiss AK, Fishbein MC, Frohlich ED (1978) Ventricular morphology and pumping ability of exercised spontaneously hypertensive rats. Am J Physiol 235 (2): H193 — H199PubMedGoogle Scholar
  15. 15.
    Weiss L (1978) Adaptive cardiovascular changes to physical training in spontaneously hypertensive and normotensive rats. Cardiovasc Res 12 (6): 329–333PubMedCrossRefGoogle Scholar
  16. 16.
    Tipton CM, Matthes RD, Callahan A, Tcheng T, Lais LT (1977) The role of chronic exercise on resting blood pressure of normotensive and hypertensive rats. Med Sci Sports 9 (3): 168–177PubMedGoogle Scholar
  17. 17.
    Evenwel R, Struyker-Boudier H (1979) Effect of physical training on the development of hypertension in the spontaneously hypertensive rat. Pflügers Arch 381: 19–24PubMedCrossRefGoogle Scholar
  18. 18.
    Shyu BC, Andersson SA, Thoren P (1984) Spontaneous running in wheels. A microprocessor assisted method for measuring physiological parameters during exercise in rodents. Acta Physiol Scand 121: 103–109Google Scholar
  19. 19.
    Friberg P, Nordlander M (1986) Influence of long-term antihypertensive therapy on cardiac function, coronary flow and myocardial oxygen consumption in spontaneously hypertensive rats. J Hypertension 4: 165–173CrossRefGoogle Scholar
  20. 20.
    Stage L (1978) Rapid determination of cardiac output in small animals from dye dilution measurements. Acta Physiol Scand 102: 43AGoogle Scholar
  21. 21.
    Friberg P (1985) Structural and functional adaptation in the rat myocardium and coronary vascular bed caused by changes in pressure and volume load. Acta Physiol Scand [Suppl 540] 124: 1–47CrossRefGoogle Scholar
  22. 22.
    Noresson E, Hallbäck M, Hjalmarsson A (1977) Structural “resetting” of the coronary vascular bed in spontaneously hypertensive rats. Acta Physiol Scand 101: 363–365PubMedCrossRefGoogle Scholar
  23. 23.
    Folkow B, Hallbäck M, Lundgren Y, Weiss L (1970) Structurally based increase of flow resistance in spontaneously hypertensive rats. Acta Physiol Scand 79: 373–378PubMedCrossRefGoogle Scholar
  24. 24.
    Göthberg G, Folkow B (1983) Age-dependent alterations in the structurally determined vascular resistance, pre-to postglomerular resistance ratio and glomerular filtration capacity in kidneys, as studied in aging normotensive rats and spontaneously hypertensive rats. Acta Physiol Scand 177: 547–555CrossRefGoogle Scholar
  25. 25.
    Nordlander M, Wâhlander H, Friberg P (1986) Myocardial and vascular structural adaptation to chronic pressure overload. J Cardiovasc Pharmacol (in press)Google Scholar
  26. 26.
    Alfaro A, Schaible TF, Malhotra A, Yipintsoi T, Scheuer J (1983) Impaired coronary flow and ventricular function in hearts of hypertensive rats. Cardiovasc Res 17: 553–561PubMedCrossRefGoogle Scholar
  27. 27.
    Braunwald E (1971) Control of myocardial oxygen consumption. Physiologic and clinical considerations. Am J Cardiol 27: 416–432PubMedCrossRefGoogle Scholar
  28. 28.
    Strauer BE (1984) The coronary circulation in hypertensive heart disease. Hypertension [Suppl III] 6: 74–80Google Scholar
  29. 29.
    Lundin SA, Hallbäck-Nordlander M (1980) Background of hyperkinetic circulatory state in young spontaneously hypertensive rats. Cardiovasc Res 14: 561–567PubMedCrossRefGoogle Scholar
  30. 30.
    Knardahl S, Sagvolden T (1979) Open-field behavior of spontaneously hypertensive rats. Behavioral and Neural Biology 27: 187–200PubMedCrossRefGoogle Scholar
  31. 31.
    Wikstrand J (1984) Left ventricular function in early primary hypertension. Functional consequences of cardiovascular structural changes. Hypertension [Suppl III] 6: 108–116Google Scholar
  32. 32.
    Lutas EM, Deveraux RB, Reis G, Alderman MH, Pickering TG, Borer JS, Laragh JH (1985) Increased cardiac performance in mild essential hypertension. Left ventricular mechanics Hypertension 7: 979–988CrossRefGoogle Scholar
  33. 33.
    Sugishita Y, Susumu K, Matsuda M, Yamaguchi T, Ito I (1983) Myocardial mechanics of athletic hearts in comparison with diseased hearts. Am Heart J 105: 273–280PubMedCrossRefGoogle Scholar
  34. 34.
    Friberg P, Folkow B, Nordlander M (1986) Cardiac dimensions in spontaneously hypertensive rats following different modes of blood pressure reduction by antihypertensive treatment. J Hypertension 4: 85–92CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1987

Authors and Affiliations

  • Peter Friberg
    • 1
  1. 1.Department of PhysiologyUniversity of GöteborgGöteborgSweden

Personalised recommendations