Electromechanical Coupling between Skeletal and Cardiac Muscle

نویسندگان

  • Hans Reinecke
  • Glen H. MacDonald
  • Stephen D. Hauschka
  • Charles E. Murry
چکیده

Skeletal myoblasts form grafts of mature muscle in injured hearts, and these grafts contract when exogenously stimulated. It is not known, however, whether cardiac muscle can form electromechanical junctions with skeletal muscle and induce its synchronous contraction. Here, we report that undifferentiated rat skeletal myoblasts expressed N-cadherin and connexin43, major adhesion and gap junction proteins of the intercalated disk, yet both proteins were markedly downregulated after differentiation into myo-tubes. Similarly, differentiated skeletal muscle grafts in injured hearts had no detectable N-cadherin or connexin43; hence, electromechanical coupling did not occur after in vivo grafting. In contrast, when neonatal or adult cardiomyocytes were cocultured with skeletal muscle, approximately 10% of the skeletal myotubes contracted in synchrony with adjacent cardiomyocytes. Isoproterenol increased myotube contraction rates by 25% in coculture without affecting myotubes in monoculture, indicating the cardiomyocytes were the pacemakers. The gap junction inhibitor heptanol aborted myotube contractions but left spontaneous contractions of individual cardiomyocytes intact, suggesting myotubes were activated via gap junctions. Confocal microscopy revealed the expression of cadherin and connexin43 at junctions between myotubes and neonatal or adult cardiomyocytes in vitro. After microinjection, myotubes transferred dye to neonatal cardiomyocytes via gap junctions. Calcium imaging revealed synchronous calcium transients in cardiomyocytes and myotubes. Thus, cardiomyocytes can form electromechanical junctions with some skeletal myotubes in coculture and induce their synchronous contraction via gap junctions. Although the mechanism remains to be determined, if similar junctions could be induced in vivo, they might be sufficient to make skeletal muscle grafts beat synchronously with host myocardium.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Electromechanical Coupling between Skeletal and Cardiac Muscle: Implications for Infarct Repair

Skeletal myoblasts form grafts of mature muscle in injured hearts, and these grafts contract when exogenously stimulated. It is not known, however, whether cardiac muscle can form electromechanical junctions with skeletal muscle and induce its synchronous contraction. Here, we report that undifferentiated rat skeletal myoblasts expressed N-cadherin and connexin43, major adhesion and gap junctio...

متن کامل

Skeletal muscle stem cells do not transdifferentiate into cardiomyocytes after cardiac grafting.

Skeletal muscle cell-derived grafts in the heart may benefit myocardial performance after infarction. Several studies have suggested that skeletal muscle stem cells (satellite cells) from adult muscle undergo transdifferentiation into cardiomyocytes after grafting into the heart, but expression of cardiac markers in graft cells has not been rigorously confirmed. To determine the fate of satelli...

متن کامل

Electromechanical coupling II. The effect of perchlorate upon excitation-contraction coupling in frog skeletal muscle fibres.

In single skeletal muscle fibres perchlorate causes a large shift of the potential dependence of contraction activation to more negative potentials without a corresponding alteration in the kinetics of the inactivation process.

متن کامل

Electromechanical coupling I. Introduction.

In skeletal muscle fibres contraction is initiated by the action potential which travels inward along the transverse tubular system and causes in some way the release of Ca from the terminal cisternae of the sarcoplasmic reticulum (SR). Ca-release is probably controlled by a potential-sensor (intram em brane charge movement) in the wall of the T-system which in a triad is about 10 20 nm apart f...

متن کامل

The effect of resistance exercise on oxidative stress in cardiac and skeletal muscle tissues of streptozotocin-induced diabetic rats

Abstract Background and Objective: It has been shown that oxidative stress increases in diabetes and it has an important role in its development and subsequent complications. Thus, the aim of this study was to investigate the effect of acute resistance exercise on oxidative stress in skeletal muscle and cardiac tissues of streptozotocin-induced diabetic rats. Materials and Methods: Twenty male ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • The Journal of Cell Biology

دوره 149  شماره 

صفحات  -

تاریخ انتشار 2000