Summary
Chronic alterations in haemodynamic load or thyroid state affect the ATPase activity of myofibrils from the rat heart. In order to determine the limits of such an adaptational reaction, the Ca2+-dependent activation of myofibrils containing only myosin V1 or V3 was investigated. These limiting states were achieved by changes in the thyroid state, i.e., myosin V1 myofibrils were obtained from 5-week-old rats, and myosin V3 myofibrils from hypothyroid rats. Analysis of the activation of myofibrillar ATPase by Ca2+ using the model-independent Hill equation showed that transition of the myosin isoenzymes neither affected Ca2+ sensitivity (pCa50%=6.52) nor positive co-operativity (n=2.4). The ATPase activity at saturating Ca2+ concentrations was 192 nMole P mg−1 min−1 in myosin V1-myofibrils and was reduced to 131 nMole P mg−1 min−1 in the case of myosin V3-myofibrils. Beside changes in the thyroid hormone state, polymorphic myosin is also influenced by chronic pressure overload and endurance training of a swimming routine. Such haemodynamically induced changes in myofibrillar ATPase were accounted for on the basis of the altered myosin isoenzyme pattern and the ATPase activities of isoenzymatically homogeneous myofibrils obtained by changes in the thyroid state. It can therefore be concluded that both haemodynamic load and thyroid state affect myofibrillar ATPase by a common mechanism, namely, by inducing a change in the isoenzyme pattern of myosin due to a redirected expression of myosin genes. Myosins from other mammals were compared with rat myosin on pyrophosphate gels. The Ca2+-dependent activation of myofibrillar ATPase from euthyroid and hypothyroid adult mice suggested the existence of a polymorphic myosin which was verified by the pyrophosphate gel technique. The mouse myosin isoenzymes were, however, less separated on pyrophosphate gels when compared with the rat myosins. It therefore seems advisable to consider both the activation properties of myofibrillar ATPase, as well as electrophoretic properties, for defining the adaptational state of myocardium of higher mammalian species.
Zusammenfassung
Die ATPase-Aktivität von Myofibrillen aus Rattenherz wird durch chronische Veränderungen in der hämodynamischen Belastung oder im Status der Schilddrüsenhormone beeinflußt. Um die Grenzen solcher Anpassungsmechanismen abzustecken, wurde die Ca2+-abhängige Aktivierung von Myofibrillen, die entweder Myosin V1 oder Myosin V3 enthielten, untersucht. Diese den Anpassungsbereich begrenzenden Zustände wurden durch Veränderungen im Spiegel der Schilddrüsenhormone erzeugt: Myosin V1-Myofibrillen wurden aus 5 Wochen alten Ratten und Myosin V3-Myofibrillen wurden aus hypothyreoten Ratten isoliert. Eine Analyse der Ca2+-abhängigen Aktivierung der Myofibrillen auf der Grundlage der Hill-Gleichung zeigte, daß weder die Ca2+-Sensitivität (pCa50%=6.52) noch die positive Kooperativität (n=2.4) verändert ist. Die ATPase-Aktivität bei Vollaktivierung war 192 nMol P mg−1 min−1 bei Myosin V1-Myofibrillen und 131 nMol P mg−1 min−1 bei Myosin V3-Myofibrillen. Neben Veränderungen im Status der Schilddrüsenhormone wird das polymorphe Myosin auch durch eine chronische Druckbelastung und durch das Ausdauertraining eines Schwimmprogrammes beeinflußt. Solche Veränderungen in der myofibrillären ATPase lassen sich erklären auf Grund des veränderten Isoenzymmusters und der ATPase-Aktivitäten von Myofibrillen, die homogen sind bezüglich der Isoenzyme, die durch Veränderungen im Status der Schilddrüsenhormone induziert wurden. Die hämodynamische Belastung und die Schilddrüsenhormone beeinflussen daher die myofibrilläre ATPase in einem beiden gemeinsamen Mechanismus: Sie führen zu einer Veränderung im Isoenzymmuster des Myosins als Folge einer veränderten Genexpression.
Die Myosine anderer Säugetiere wurden mit Hilfe der Pyrophosphat-Gel-Elektrophorese mit dem Myosin der Ratte verglichen. Die Ca2+-abhängige Aktivierung der myofibrillären ATPase von euthyreoten und hypothyreoten, erwachsenen Mäusen legte ein polymorphes Myosin nahe, das mit Hilfe der Pyrophosphat-Gel-Elektrophorese bestätigt wurde. Die Auftrennung der Myosin-Isoenzyme der Maus war jedoch geringer als die der Ratte. Es wird daher empfohlen, die Ca2+-abhängige Aktivierung der myofibrillären ATPase neben elektrophoretischer Eigenschaften für die Charakterisierung des myokardialen Anpassungszustandes höherer Säugetiere heranzuziehen.
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References
Jacob, R., G. Kissling: Left ventricular dynamics and myocardial function in Goldblatt hypertension of the rat. Biochemical, morphological and electrophysiological correlates. In: The Heart in Hypertension, Strauer, B. E. (ed.) 89–107. Springer-Verlag, (Berlin-Heidelberg-New York 1981).
Jacob, R., G. Kissling, G. Ebrecht, C. Holubarsch, I. Medugorac, H. Rupp: Adaptive and pathological alterations in experimental cardiac hypertrophy. Advan. Myocardiol. (in the press).
Yazaki, Y., M. S. Raben: Effect of the thyroid state on the enzymatic characteristics of cardiac myosin. Circ. Res.36, 208–215 (1975).
Hoh, J. F. Y., P. A. McGrath, P. T. Hale: Electrophoretic analysis of multiple forms of rat cardiac myosin: Effects of hypophysectomy and thyroxine replacement. J. Mol. Cell. Cardiol.10, 1053–1076 (1978).
Sartore, S., S. Pierobon-Bormioli, S. Schiaffino: Immunohistochemical evidence for myosin polymorphism in the chicken heart. Nature274, 82–83 (1978).
Flink, I. L., J. H. Rader, E. Morkin: Thyroid hormone stimulates synthesis of a cardiac myosin isozyme. J. Biol. Chem.254, 3105–3110 (1979).
Lompre, A.-M., K. Schwartz, A. d'Albis, G. Lacombe, N. Van Thiem, B. Swynghedauw: Myosin isoenzyme redistribution in chronic heart overload. Nature282, 105–107 (1979).
Rupp, H.: The adaptive changes in the isoenzyme pattern of myosin from hypertrophied rat myocardium as a result of pressure overload and physical training. Basic Res. Cardiol.76, 79–88 (1981).
Rupp, H., G. Kissling, R. Jacob: The hormonal and haemodynamic determinants of polymorphic myosin. In: Biology of Myocardial Hypertrophy and Failure, Alpert, N. R. (ed.) (Raven Press, New York, in the press).
Kissling, G., T. Gassenmaier, M. F. Wendt-Gallitelli, R. Jacob: Pressure-volume relations, elastic modulus, and contractile behaviour of the hypertrophied left ventricle of rats with Goldblatt II hypertension. Pflügers Arch.369, 213–221 (1977).
Rupp, H.: Modulation of tension generation at the myofibrillar level — an analysis of the effect of magnesium adenosine triphosphate, magnesium, pH, sarcomere length and state of phosphorylation. Basic Res. Cardiol.75, 295–317 (1980).
Rupp, H.: Cooperative effects of calcium on myofibrillar ATPase of normal and hypertrophied heart. Basic Res. Cardiol.75, 157–162 (1980).
Walker, P., J. D. Dubois, J. H. Dussault: Free thyroid hormone concentrations during postnatal development in the rat. Pediat. Res. 14, 247–249 (1980).
Hoh, J. F. Y., G. P. S. Yeoh, M. A. W. Thomas, L. Higginbottom: Structural differences in the heavy chains of rat ventricular myosin isoenzymes. FEBS Lett.97, 330–334 (1979).
Walker, P., M. E. Weichsel, Jr., D. A. Fisher, S. M. Guo, D. A. Fisher: Thyroxine increases nerve growth factor concentration in adult mouse brain. Science204, 427–429 (1979).
Seyfried, T. N., G. H. Glaser, R. K. Yu: Thyroid hormone influence on the susceptibility of mice to audiogenic seizures. Science205, 598–600 (1979).
Dussault, J. H., P. Walker: The effect of iodine deficiency and propylthiouracil on the hypothalamo-pituitary-thyroid axis in the neonatal rat. Can. J. Physiol. Pharmacol.56, 950–955 (1978).
Maennistoe, P. T., T. Ranta, J. Leppaeluoto: Effects of methylmercaptoimidazole (MMI), propylthiouracil (PTU), potassium perchlorate (KClO4) and potassium iodide (KI) on the serum concentrations of thyrotrophin (TSH) and thyroid hormones in the rat. Acta Endocrinol.91, 271–281 (1979).
Rupp, H.: Ca2+-dependent activation of cardiac myofibrils — the mechanisms which modulate myofibrillar ATPase and tension and their significance for heart function. Advan. Myocardiol. (in the press).
Rupp, H.: The determinants of the Ca2+-activation of myofilaments from rat heart. Mol. Physiol. (submitted).
Tawada, Y., K. Tawada: Co-operative regulation mechanism of muscle contraction: inter-tropomyosin co-operation model. J. Theor. Biol.50, 269–283 (1975).
Ray, K. P., P. J. England: Phosphorylation of the inhibitory subunit of troponin and its effect on the calcium dependence of cardiac myofibril adenosine triphosphatase. FEBS Lett.70, 11–16 (1976).
Jacob, R., G. Ebrecht, C. Holubarsch, H. Rupp, G. Kissling: Mechanics and energetics in cardiac hypertrophy as related to the isoenzyme pattern of myosin. In: Biology of Myocardial Hypertrophy and Failure, Alpert, N. R. (ed.) Raven Press (New York) (in the press).
Alpert, N. R., H. H. Gale, N. Taylor: The effect of an age on contractile protein ATPase activity and the velocity of shortening. In: Factors Influencing Myocardial Contractility, Tanz, R. D., F. Kavaler, J. Roberts (eds.) 127–133 Academic Press (New York 1967).
Heller, L. J., W. V. Whitehorn: Age-associated alterations in myocardial contractile properties. Am. J. Physiol.222, 1613–1619 (1972).
Chesky, J. A., M. Rockstein: Reduced myocardial actomyosin adenosine triphosphatase activity in the ageing male Fischer rat. Cardiovascular Res.11, 242–246 (1977).
Kämmereit, A., R. Jacob: Alterations in rat myocardial mechanics under Goldblatt hypertension and experimental aortic stenosis. Basic Res. Cardiol.74, 389–405 (1979).
Yazaki, Y., M. S. Raben: Cardiac myosin adenosinetriphosphatase of rat and mouse. Circ. Res.35, 15–23 (1974).
Delcayre, C., B. Swynghedauw: A comparative study of heart myosin. ATPase and light subunits from different species. Pflügers Arch.355, 39–47 (1975).
Morkin, E.: Stimulation of cardiac myosin adenosine triphosphatase in thyrotoxicosis. Circ. Res.44, 1–7 (1979).
Lompre, A. M. J. J. Mercadier, C. Wisnewsky, P. Bouveret, C. Pantaloni, A. d'Albis, K. Schwartz: Species and age-dependent distribution of mammalian cardiac myosin isoenzymes. 9th European Congress on Muscle and Motility (Salzburg 1980), Abstract 98.
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Rupp, H. Polymorphic myosin as the common determinant of myofibrillar ATPase in different haemodynamic and thyroid states. Basic Res Cardiol 77, 34–46 (1982). https://doi.org/10.1007/BF01908129
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DOI: https://doi.org/10.1007/BF01908129