- Email: [email protected]
Vinculin-containing costameres: Parts of contraction forces transmitting site of cardiomyocyte
J MoI
Cell
Cardiol
24
(Supplement
II)
(1992)
p-6
CARDIAC GROWTHRESPONSE TO WORKLOAD INDUCED AT DIPPEREN TAGES. J. Slezak, A. Randhawa*, L. Zlatos and P.K. Singal*. Inst. for Heart Res., Slav. Acad. Sci., Bratislava, Czech and Slovak Federative Republik. *St. B. Research Centre, University of Manitoba, Winnipeg, Canada. Pressure overload in neonatal puppies (2 days old) and adult guinea pigs (22 days old) was induced by constriction of the aorta. In puppies, all studies were done on hearts removed between 7th and 42nd day postoperation at one week intervals. Comparison of the water and hydroxyproline (HP) content in the myocardium of experimental and age matched control animals confirmed that the increase in heart weight of experimental puppies was neither due to increased hydration nor proliferation of the connective tissue but was due to increased muscle mass. Changes in the concentration and content of DNA showed that the compensatory myocardial mass gain during the first 3 weeks of life correlated with an increase in the number of muscle cells After this period, muscle cell hypertrophy became the predominant mechanism of adaption to sustained work overload. Under physiological conditions hyperplasia was found to decrease substantially by the end of the first week, however, proteosynthesis, myofibrilogenesis and mitochondriogenesis were intensely stimulated up to the end of the third week of postnatal life and remained so even in the later period under study. On the other hand, in guinea pigs, there was 60 and 140% increase respectively in HP content at 10 and 20 weeks postoperation. This collagen increase in the lo-week functionally compensated hearts, was mainly perivascular while in the 20-week failing hearts, intermyofibrillar as well as focal deposition of collagen was noticed. Study emphasizes heterogeneity of the growth response depending on the species as well as age of the animal. (Supported partially by the Medical Research Council of Canada).
P-7
EFFECTS OF MONOCROTALINE-INDUCED PULMONARY HYPERTENSION ON RIGHT VENTRICULAR HEMODYNAMIC, BIOCHEMICAL AND HISTOLOGICAL CHANGES Y Hirota, M. Nagai, M. Nagano. Department of Internal Medicine, Aoto Hospital, Jikei University School of Medicine, Tokyo, Japan. Hemodynamic, biochemical and histological changes were examined in rats with monocrotalinc (MCT)-induced pulmonary hypertension. MCT (40 mg./kg) was injection into male SpragueDawley rats (180-200 g) to induce pulmonary hypertension. Hearts were excised 1,2 and 4 weeks after the injection of MCI and age-matched untreated rats served as controls. ECG changes of right ventricular hypertrophy were recognized after 4 weeks of MCT injection. Right ventricular peak pressure and dP/dtmax were increased after 2 weeks of MCT injection. Right ventricular myosin isoenzyme patterns were shifted toward V3 in hypertrophied right ventricle. Macro-and microscopic examination revealed remarkable dilatation of the right ventricle after 2 weeks of MCT administration. These results demonstrated that Ma-induced pulmonary hypertension caused right ventricular hypertrophy associated with significant myocardial hemodynamic, biochemical and histological alterations.
p-6
VINCULIN-CONTAINING COSTAMERES : PARTS OF CONTRACTION FORCES TRANSMJTTING SITE OF CARDIOMYOCYTE. K. Imanaka-Yoshida, B.A. Danowski. J. M. Sanger, J. W. Sanger, T. Yoshida, K. Izutsu and T. Nakano. Department of Pathology and 1st Internal Medicine Mie University School of Medicine, Tsu, Japan and Department of Anatomy, University of Pennsylvania, School of Medicine, Philadelphia, U.S.A. A technique using a easily deformable flexible silicon rubber is useful to observe contraction forces of cultured cells. When abult rat cardiomyocytes are. cultured on the silicone rubber substratum, How do the they form a series of fine pleat-like wrinkles of the substratum in response of beating. In order to wrinkles relate to myofibrils and the distribution of adhesion plaque protein, vinculin? answer this question, we microinjected fluorescently labeled alpha-actinin and vinculin to visualize Z-lines and costameres respectively. The periodicity of the wrinkles was coincident with the spacing ‘Costamere’, a banded of Z-lines, as determined by the localization of fluorescent alpha-actinin. pattern of vinculin which co-localizes with Z-lines, was detected in the area where pleat-like winkles formed. Interference reflection microscopic images of the cells showed banded dark close contacts These indicate that myofibrils are linked to substratum at Z-lines corresponding to costameres. by costameres containing vinculin and that contraction forces can be also transmitted to extracellular matrix through costameres. S.52
Cell
Cardiol
24
(Supplement
II)
(1992)
p-6
CARDIAC GROWTHRESPONSE TO WORKLOAD INDUCED AT DIPPEREN TAGES. J. Slezak, A. Randhawa*, L. Zlatos and P.K. Singal*. Inst. for Heart Res., Slav. Acad. Sci., Bratislava, Czech and Slovak Federative Republik. *St. B. Research Centre, University of Manitoba, Winnipeg, Canada. Pressure overload in neonatal puppies (2 days old) and adult guinea pigs (22 days old) was induced by constriction of the aorta. In puppies, all studies were done on hearts removed between 7th and 42nd day postoperation at one week intervals. Comparison of the water and hydroxyproline (HP) content in the myocardium of experimental and age matched control animals confirmed that the increase in heart weight of experimental puppies was neither due to increased hydration nor proliferation of the connective tissue but was due to increased muscle mass. Changes in the concentration and content of DNA showed that the compensatory myocardial mass gain during the first 3 weeks of life correlated with an increase in the number of muscle cells After this period, muscle cell hypertrophy became the predominant mechanism of adaption to sustained work overload. Under physiological conditions hyperplasia was found to decrease substantially by the end of the first week, however, proteosynthesis, myofibrilogenesis and mitochondriogenesis were intensely stimulated up to the end of the third week of postnatal life and remained so even in the later period under study. On the other hand, in guinea pigs, there was 60 and 140% increase respectively in HP content at 10 and 20 weeks postoperation. This collagen increase in the lo-week functionally compensated hearts, was mainly perivascular while in the 20-week failing hearts, intermyofibrillar as well as focal deposition of collagen was noticed. Study emphasizes heterogeneity of the growth response depending on the species as well as age of the animal. (Supported partially by the Medical Research Council of Canada).
P-7
EFFECTS OF MONOCROTALINE-INDUCED PULMONARY HYPERTENSION ON RIGHT VENTRICULAR HEMODYNAMIC, BIOCHEMICAL AND HISTOLOGICAL CHANGES Y Hirota, M. Nagai, M. Nagano. Department of Internal Medicine, Aoto Hospital, Jikei University School of Medicine, Tokyo, Japan. Hemodynamic, biochemical and histological changes were examined in rats with monocrotalinc (MCT)-induced pulmonary hypertension. MCT (40 mg./kg) was injection into male SpragueDawley rats (180-200 g) to induce pulmonary hypertension. Hearts were excised 1,2 and 4 weeks after the injection of MCI and age-matched untreated rats served as controls. ECG changes of right ventricular hypertrophy were recognized after 4 weeks of MCT injection. Right ventricular peak pressure and dP/dtmax were increased after 2 weeks of MCT injection. Right ventricular myosin isoenzyme patterns were shifted toward V3 in hypertrophied right ventricle. Macro-and microscopic examination revealed remarkable dilatation of the right ventricle after 2 weeks of MCT administration. These results demonstrated that Ma-induced pulmonary hypertension caused right ventricular hypertrophy associated with significant myocardial hemodynamic, biochemical and histological alterations.
p-6
VINCULIN-CONTAINING COSTAMERES : PARTS OF CONTRACTION FORCES TRANSMJTTING SITE OF CARDIOMYOCYTE. K. Imanaka-Yoshida, B.A. Danowski. J. M. Sanger, J. W. Sanger, T. Yoshida, K. Izutsu and T. Nakano. Department of Pathology and 1st Internal Medicine Mie University School of Medicine, Tsu, Japan and Department of Anatomy, University of Pennsylvania, School of Medicine, Philadelphia, U.S.A. A technique using a easily deformable flexible silicon rubber is useful to observe contraction forces of cultured cells. When abult rat cardiomyocytes are. cultured on the silicone rubber substratum, How do the they form a series of fine pleat-like wrinkles of the substratum in response of beating. In order to wrinkles relate to myofibrils and the distribution of adhesion plaque protein, vinculin? answer this question, we microinjected fluorescently labeled alpha-actinin and vinculin to visualize Z-lines and costameres respectively. The periodicity of the wrinkles was coincident with the spacing ‘Costamere’, a banded of Z-lines, as determined by the localization of fluorescent alpha-actinin. pattern of vinculin which co-localizes with Z-lines, was detected in the area where pleat-like winkles formed. Interference reflection microscopic images of the cells showed banded dark close contacts These indicate that myofibrils are linked to substratum at Z-lines corresponding to costameres. by costameres containing vinculin and that contraction forces can be also transmitted to extracellular matrix through costameres. S.52