Role of microtubules in the contractile dysfunction of myocytes from tachycardia-induced dilated cardiomyopathy

Masaru Takahashi, Hiroyuki Tsutsui, Shintaro Kinugawa, Keiko Igarashi-Saito, Shimako Yamamoto, Mitsutaka Yamamoto, Hirofumi Tagawa, Kyoko Imanaka-Yoshida, Kensuke Egashira, Akira Takeshita

Research output: Contribution to journalArticle

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Abstract

Microtubules of cardiac myocytes are increased in pressure-overloaded cardiac hypertrophy, which interfere with the actin-myosin crossbridge motion and depress muscle contractility. However, it is unknown whether microtubules are increased in non-hypertrophied, dilated cardiomyopathy and, if so, their increase could contribute to the depressed contractility. We assessed the contractile function of isolated left-ventricular (LV) myocytes and also quantitated tubulin mRNA levels as well as free and polymerized tubulin proteins using the LV myocardium obtained from dogs with rapid pacing (240 beats/min, 4 weeks)-induced dilated failing cardiomyopathy (HF; n = 6) and control dogs (n = 6). Myocyte contractility was significantly depressed in HF compared to control. Northern blot analysis indicated that tubulin mRNA levels (normalized to GAPDH mRNA) in HF dogs were upregulated (0.43 ± 0.04 v 0.13 ± 0.02; P < 0.01). In contrast, the amount of total tubulins (633 ± 52 v 697 ± 42 μg/g wet weight; P = N.S.) and the ratio of polymerized tubulin fraction-to-total tubulin (0.44 ± 0.02 v 0.44 ± 0.01; P = N.S.) did not differ between the two groups. Immunohistochemical studies showed no apparent differences in the distribution or density of intracellular microtubule network. Further, the exposure of myocytes to colchicine (1 μmol/l, 30 min), which depolymerizes microtubules, did not promote any improvement of the depressed myocyte contraction. Pacing-induced tachycardia increased myocardial tubulin mRNA, but the amount of total and polymerized tubulins were not increased, indicating that alterations in myocyte microtubules do not contribute to the contractile abnormalities in this model of HF.

Original languageEnglish
Pages (from-to)1047-1057
Number of pages11
JournalJournal of Molecular and Cellular Cardiology
Volume30
Issue number5
DOIs
Publication statusPublished - Jan 1 1998

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Dilated Cardiomyopathy
Tubulin
Tachycardia
Microtubules
Muscle Cells
Messenger RNA
Dogs
Colchicine
Cardiomegaly
Myosins
Left Ventricular Function
Cardiac Myocytes
Northern Blotting
Actins
Myocardium
Pressure
Weights and Measures
Muscles

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this

Role of microtubules in the contractile dysfunction of myocytes from tachycardia-induced dilated cardiomyopathy. / Takahashi, Masaru; Tsutsui, Hiroyuki; Kinugawa, Shintaro; Igarashi-Saito, Keiko; Yamamoto, Shimako; Yamamoto, Mitsutaka; Tagawa, Hirofumi; Imanaka-Yoshida, Kyoko; Egashira, Kensuke; Takeshita, Akira.

In: Journal of Molecular and Cellular Cardiology, Vol. 30, No. 5, 01.01.1998, p. 1047-1057.

Research output: Contribution to journalArticle

Takahashi, M, Tsutsui, H, Kinugawa, S, Igarashi-Saito, K, Yamamoto, S, Yamamoto, M, Tagawa, H, Imanaka-Yoshida, K, Egashira, K & Takeshita, A 1998, 'Role of microtubules in the contractile dysfunction of myocytes from tachycardia-induced dilated cardiomyopathy', Journal of Molecular and Cellular Cardiology, vol. 30, no. 5, pp. 1047-1057. https://doi.org/10.1006/jmcc.1998.0674
Takahashi, Masaru ; Tsutsui, Hiroyuki ; Kinugawa, Shintaro ; Igarashi-Saito, Keiko ; Yamamoto, Shimako ; Yamamoto, Mitsutaka ; Tagawa, Hirofumi ; Imanaka-Yoshida, Kyoko ; Egashira, Kensuke ; Takeshita, Akira. / Role of microtubules in the contractile dysfunction of myocytes from tachycardia-induced dilated cardiomyopathy. In: Journal of Molecular and Cellular Cardiology. 1998 ; Vol. 30, No. 5. pp. 1047-1057.
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