Abstract
The purpose of the present investigation was to determine the effects of thyroxine (T4) induced myocardial hypertrophy on coronary flow reserve, O2 extraction reserve and the reserve of unperfused capillaries. Studies were conducted in anesthetized open chest New Zealand white rabbits. One group had blood flow determined with radioactive microspheres and O2 extraction determined microspectrophotometrically. Reserves were tested with hypoxia. In the other group, FITC-dextran was injected to label the perfused microvessels. An alkaline phosphatase stain was employed to locate the total microvascular bed. O2 consumption increased 280% in the 16-day T4 group and this was accompanied by significant increases in coronary flow and O2 extraction. Blood flow further increased 101% for the hypoxic 16-day T4 group. Venous O2 saturation also decreased significantly in hypoxia. There were 2544 ± 210 capillaries/mm2 and 5 ± 1 arterioles/mm2 in control subendocardium. These decreased significantly to 1457 ± 65/mm2 and 1 ± 1/mm2 respectively after 16 days of T4. In controls, 59 ± 2% of the capillaries and 56 ± 9% of the arterioles were perfused in the subendocardium. This increased significantly to 88 ± 3% and 79 ± 8% respectively by 16 days of T4 treatment. Thus, the physiological response to the increased work and decreased capillary density is to increase the proportion of the capillary bed perfused to at least maintain physiological diffusion distances. The T4 hypertrophied hearts were also able to increase their blood flow and decrease their venous O2 saturation in response to further stress.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Graettinger JS, Muenster JJ, Selverstone LA, Campbell JA (1959): A correlation of clinical and hemodynamic studies in patients with hyperthyroidism with and without congestive heart failure. J Clin Invest 38: 1316–1327.
Skelton CL, Coleman H, Wildenthal K, Braunwald E (1970): Augmentation of myocardial oxygen consumption in hyperthyroid cats. Circ Res 27: 301–309.
Talafih K, Briden KL, Weiss HR (1983): Thyroxine-induced hypertrophy of the rabbit heart - effect on regional O2 extraction, flow and O2 consumption. Circ Res 52: 272–279.
Edgren J, von Knorring J, Lindy S, Torto H (1976): Heart volume and myocardial connective tissue during development and regression of thyroxine-induced cardiac hypertrophy in rats. Acta Physiol Scand 97: 514–518.
Gemmill CL (1956): Metabolic effects of thyroxine, 3,3′,5-triiodothyronine, 3,3′-diiodo-5-bromothyronine and 3,3′,5-diiodothyronine administered orally to rats. Am J Physiol 187: 323–327.
Piatnek-Leunissen K, Olson RE (1967): Cardiac failure in the dog as a consequence of exogenous hyperthyroidism. Circ Res 20: 242–252.
Leight L, DeFrazio V, Talmers FN, Hellems HK (1956): Coronary blood flow myocardial oxygen consumption, and myocardial metabolism in normal and hyperthryroid human subjects. Circulation 14: 90–99.
Holtz J, Grunewald A, Manz R, Restoroff WV, Bassenge E (1977): Intracapillary hemoglobin oxygen saturation of oxygen consumption in different layers of the left ventricular myocardium. Pflügers Archiv 370: 253–258.
Marcus ML, Mueller TM, Fascho JA, Kerber RE (1979): Effects of cardiac hypertrophy secondary to hypertension on the coronary circulation. Am J Cardiol 44: 1023–1038.
Wangler RD, Peters KG, Marcus ML, Tomenek RJ (1982): Effects of duration and severity of arterial hypertension and cardiac hypertrophy on coronary vasodilator reserve. Circ Res 51: 10–18.
Talafih K, Grover GJ, Weiss HR (1984): Effect of T4-induced cardiac hypertrophy on O2 supply-consumption balance during normoxia and hypoxia. Am J Physiol 246: H374-H379.
Anversa P, Olivetti G, Melissari M, Loud AV (1979): Morphometric study of myocardial hypertrophy induced by abdominal aortic stenosis. Lab Invest 40: 341–349.
Breisch EA, Bove AA, Phillips SJ (1980): Myocardial morphometrics in pressure overload left ventricular hypertrophy and regression. Cardiovasc Res 14: 161–168.
McCallister LP, Page E (1973): Effects of thyroxine on ultrastructure of rat myocardial cells. A stereological study. J Ultrastruc Res 42: 136–155.
Olivetti G, Anversa P, Loud AV (1980): Morphometric study of early postnatal development in the left and right ventricular myocardium of the rat. II. Tissue composition, capillary growth, and sarcoplasmic alterations. Circ Res 46: 503–512.
Rakusan K, Hrdina PW, Turek Z, Lakatta G, Spurgeon HA, Wolford GD (1984): Cell size and capillary supply of the hypertensive rat: quantitative study. Basic Res Cardiol 79: 389–395.
Tomanek RJ (1980): The relative distribution of coronary blood flow in rats with moderate and marked left ventricular hypertrophy. Can J Physiol Pharmacol 58: 830–835.
Tomanek RJ, Searls JC, Lachenbruch PA (1982): Quantitative changes in the capillary bed during developing, peak, and stabilized cardiac in the spontaneously hypertensive rat. Circ Res 51: 295–304.
Anversa P, Melissari M, Beghi C, Olivetti G (1984): Structural compensatory mechanisms in rat heart in early spontaneous hypertension. Am J Physiol 246: H739-H746.
Wright AJA, Hudlicka O (1981): Capillary growth and changes in heart performance induced by chronic bradycardial pacing in the rabbit. Circ Res 49: 469–478.
Crystal GJ, Downey HF, Bashour FA (1981): Small vessel and total coronary blood volume during intracoronary adenosine. Am J Physiol 241: H194-H201.
Duran WN, Marsicano TH, Anderson RW (1977): Capillary reserve in isometrically contracting dog heart. Am J Physiol 232: H276-H281.
Martini J, Honig CR (1969): Direct measurement of intercapillary distances in beating rat heart in situ under various conditions of O2 supply. Microvasc Res 1: 244–256.
Weiss HR, Conway RS (1985): Morphometric study of the total and perfused arteriolar and capillary network of the rabbit left ventricle. Cardiovasc Res 19: 343–354.
Weiss HR, Winbury MM (1974): Nitroglycerin and chromonar on small vessel blood content of the ventricular walls. Am J Physiol 226: 838–843.
Steinhausen M, Tillmans H, Thederan H (1978): Microcirculation of the epimyocardial layer of the heart. I. A method for in vivo observation of the microcirculation of superficial ventricular myocardium of the heart and capillary flow pattern under normal and hypoxic conditions. Pflügers Archiv 378: 9–14.
Vetterlein F, Dal Ri H, Schmidt G (1982): Capillary density in rat myocardium during timed plasma staining. Am J Physiol 242: H133-H141.
Kleinert HD, Scales JL, Weiss HR (1980): Effect of carbon monoxide or low oxygen gas mixture inhalation on regional oxygenation, blood flow, and small vessel blood content of the rabbit heart. Pflügers Archiv 383: 105–111.
Weiss HR, Sinha AK (1978): Regional oxygen saturation in small arteries and veins in the canine myocardium. Circ Res 42: 119–126.
Underwood EE (1970): Quantitative stereology. Addison-Wesley Publishing Co, Reading.
Weibel ER (1979): Stereological methods, vol. 1, Practical methods for biological morphometry. Academic Press, London.
Gunning JF, Harrsion CE, Coelman HN (1974): Myocardial contractility and energetics following treatment with d-thyroxine. Am J Physiol 226: 1166–1171.
Malik AB, Abe T, O’Kane HO, Geha AS (1973): Cardiac function, coronary flow, and oxygen consumption in stable left ventricular hypertrophy. Am J Physiol 225: 186–191.
White FC, Badke FR, Covell JW, LeWinter M, Bloor CM (1979): Regional myocardial blood flow in volume overload hypertrophy. J Mol Cell Cardiol 11 (Suppl 1): 66.
Powers ER, Powell WJ (1973): Effect of arterial hypoxia on myocardial oxygen consumption. Circ Res 33: 749–756.
Vrobel TR, Ring WS, Anderson RW, Emery RW, Bache RJ (1980): Effect of heart rate on myocardial blood flow in dogs with left ventricular hypertrophy. Am J Physiol 239: H621-H627.
Guski H, Meerson FZ, Wassilew G (1981): Comparative study of ultrastructure and function of the rat heart hypertrophied by exercise or hypoxia. Exp Pathol 201:108–126.
Goldman S, Olajos M, Friedman H, Roeske WR, Morkin E (1982): Left ventricular performance in conscious thyrotoxic calves. Am J Physiol 282: H113-H121.
Chilian WM, Wangler RD, Peters KG, Tomanek RJ, Marcus ML (1985): Thyroxine-induced left ventricular hypertrophy in the rat: Anatomical and physiological evidence for angiogenesis. Circ Res 57: 591–598.
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1987 Martinus Nijhoff Publishers, Dordrecht
About this chapter
Cite this chapter
Weiss, H.R., Grover, G.J. (1987). Coronary reserves in myocardial hypertrophy. In: Sideman, S., Beyar, R. (eds) Activation, Metabolism and Perfusion of the Heart. Developments in Cardiovascular Medicine, vol 70. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-3313-2_36
Download citation
DOI: https://doi.org/10.1007/978-94-009-3313-2_36
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-7987-7
Online ISBN: 978-94-009-3313-2
eBook Packages: Springer Book Archive