- Email: [email protected]
Ultrastructural studies in experimental myocardial hypertrophy
j Mol Cell Cardiol 19 (Supplement I) (1987)
L-4
Ultrastructural studies in experimental myocardial hypertrophy Jutta Schaper, B. Winkler, W. Schaper Max-Planck-Institute, Department of Experimental Cardiology, D-6350 Bad Nauheim, FRG Experimentally, cardiac hypertrophy (hyp) can be induced in different animal models such as SHR or Goldblatt rats, aortic constriction, and chronic volume overloading by aorto-caval fistula or by AV-bloek. Morphologically, developing experimental models are characterized by an increase in myocardial cell size (measured either as fiber diameter or as cell surface area) and by an enlarged amount of fibrous tissue. Ultrastructural changes are: increase of nuclear size and abnormal chromatin distribution, mitochondria of varying size and shape, Z-line alterations as well as irregularities in the sarcomere structure, abnormal configuration of the intercalated disc. Morphometric data like volume densities of mitochondria (vvmit), contractile material (Vvmyo), and cytoplasm (Vvcyt) are either increasing or decreasing. Results were obtained from dog hearts with chronic volume overloading induced by total AV-block for 2 or 12 weeks. They were analyzed with respect to Vvmit, Vvmyo, and Vvcyt as well as the capillary density. The heart weight/body weight ratio was significantly increased after 12 weeks but not at 2 weeks (control: 0.84, 2 weeks: 1.01, 12 weeks: 1.31) indicating cardiac hyp. Vvmit was increased at 2 weeks indicating a metabolic adaptation to increased work load. Capillary density as well as capillary luminal density (Vvcap lumen) were elevated at 2 weeks not at 12 weeks, indicating a very early response of the coronary microvasculature. This finding was confirmed by autoradiography. At 12 weeks apparently a compensatory stage of the development of cardiac hyp had been reached. Late stages of cardiac hyp were investigated morphometrically from biopsies of patients undergoing aortic valve replacement. Vvmyo was reduced from 58 % in normal myocardium to 40 % in longstanding hyp, in contrast to an increase in the amount of fibrosis. Late stages of hyp are characterized by deteriorating myocardium which may explain the reduced contractile function in these patients. Variable quantitative data in experimental hyp emphasize the progressive process of hyp in different stages.
S.10
L-4
Ultrastructural studies in experimental myocardial hypertrophy Jutta Schaper, B. Winkler, W. Schaper Max-Planck-Institute, Department of Experimental Cardiology, D-6350 Bad Nauheim, FRG Experimentally, cardiac hypertrophy (hyp) can be induced in different animal models such as SHR or Goldblatt rats, aortic constriction, and chronic volume overloading by aorto-caval fistula or by AV-bloek. Morphologically, developing experimental models are characterized by an increase in myocardial cell size (measured either as fiber diameter or as cell surface area) and by an enlarged amount of fibrous tissue. Ultrastructural changes are: increase of nuclear size and abnormal chromatin distribution, mitochondria of varying size and shape, Z-line alterations as well as irregularities in the sarcomere structure, abnormal configuration of the intercalated disc. Morphometric data like volume densities of mitochondria (vvmit), contractile material (Vvmyo), and cytoplasm (Vvcyt) are either increasing or decreasing. Results were obtained from dog hearts with chronic volume overloading induced by total AV-block for 2 or 12 weeks. They were analyzed with respect to Vvmit, Vvmyo, and Vvcyt as well as the capillary density. The heart weight/body weight ratio was significantly increased after 12 weeks but not at 2 weeks (control: 0.84, 2 weeks: 1.01, 12 weeks: 1.31) indicating cardiac hyp. Vvmit was increased at 2 weeks indicating a metabolic adaptation to increased work load. Capillary density as well as capillary luminal density (Vvcap lumen) were elevated at 2 weeks not at 12 weeks, indicating a very early response of the coronary microvasculature. This finding was confirmed by autoradiography. At 12 weeks apparently a compensatory stage of the development of cardiac hyp had been reached. Late stages of cardiac hyp were investigated morphometrically from biopsies of patients undergoing aortic valve replacement. Vvmyo was reduced from 58 % in normal myocardium to 40 % in longstanding hyp, in contrast to an increase in the amount of fibrosis. Late stages of hyp are characterized by deteriorating myocardium which may explain the reduced contractile function in these patients. Variable quantitative data in experimental hyp emphasize the progressive process of hyp in different stages.
S.10