Proliferation of striated muscle, either in the form of regeneration of damaged tissue or hyperplasia of relatively normal cells, is generally thought not to occur. Such an opinion is an example of the general idea that more " specialized " tissues differ from less " differentiated " tissues in that they are unable to multiply in adult life. This proposition, however, has gradually become more ...

The aim of this study was to evaluate utilization of chemical energy in relation to myocardial mechanics in variably afterloaded contractions of cardiac muscle by determining total energy utilization (—P) in the absence of energy production. Right ventricular papillary muscles of cats were equilibrated at 26°C in a myograph in Krebs' solution while contracting isometrically (12/ min). Following...

The mechanism of reentrant ventricular tachycardia was studied in computer simulations and in thin (z20x20x0.5-mm) slices of dog and sheep ventricular epicardial muscle. A two-dimensional matrix consisting of 96x96 electrically coupled cells modeled by the FitzHugh-Nagumo equations was used to analyze the dynamics of self-sustaining reentrant activity in the form of elliptical spiral waves indu...

The transcriptional activation mechanisms that regulate tissue-specific expression of cardiac muscle genes have been extensively investigated, but little is known of the regulatory events involved in repression of cardiac-specific genes in non-cardiac cells. We have previously reported that Nished, a ubiquitous transcription factor, interacts with a positive sequence element, the Intron Regulat...

Cardiac troponin T (cTnT) and troponin I (cTnI) are cardiac regulatory proteins that control the calcium mediated interaction between actin and myosin [1]. The troponin complex consists of three subunits: troponin C, troponin I, and troponin T. This complex is located on the myofibrillar thin (actin) filament of striated (skeletal and cardiac) muscle. The cardiac isoforms troponin T and I are o...

W hen a muscle is stimulated electrically, its ability to contract rises and then falls. It is conceptually easy to imagine, therefore, that something called the "active state" might rise and fall with a well-defined time course. Although the concept is simple, the attempts to measure this time course have produced such conflicting results that the whole concept has fallen into disrepute.1 Thes...

Selective comparative investigations into the uhrastructure of cardiac muscle have yielded m u c h information regarding the existence in cardiac muscle of a n u m b e r of discrete subcellular components that are common to the hearts of most, if not all, of a variety of different vertebrates.

Myofibrils in vertebrate cardiac and skeletal muscles are characterized by groups of proteins arranged in contractile units or sarcomeres, which consist of four major components - thin filaments, thick filaments, titin and Z-bands. The thin actin/tropomyosin-containing filaments are embedded in the Z-bands and interdigitate with the myosin-containing thick filaments aligned in A-bands. Titin is...

• Relationships between cardiac and hypophyseal functions have been recognized since early clinical observations of cardiac enlargement and failure in acromegaly. Experimental attention has been directed at hypophyseal influences on cardiac size," cardiac output,' and the ability of the heart to hypertrophy." The relationship of cardiac changes to peripheral circulatory events following hypophy...

We have isolated a full length complementary DNA clone (pCTnC1) from a 19-day embryonic chicken heart library corresponding to cardiac troponin C (TnC). Sequence analysis demonstrated varying homologies with TnC complementary DNA clones isolated from developing chick skeletal muscle. Using pCTnC1 as a hybridization probe, we have determined that cardiac TnC is constitutively expressed in both a...