ATP is required for normal cardiac contractile function, and it has long been hypothesized that reduced energy delivery contributes to the contractile dysfunction of heart failure (HF). Despite experimental and clinical HF data showing reduced metabolism through cardiac creatine kinase (CK), the major myocardial energy reserve and temporal ATP buffer, a causal relationship between reduced ATP-C...

The relationship between lactic acid concentration and twitch tension was reevaluated in electrically stimulated frog sartorius muscle. In muscles stimulated under anaerobic conditions at a rate of 30 stimuli/MIN CONTRACTILE FORCE DECREASED TO 36% OF THE INITIAL VALUE IN 15 MIN, Concomitantly lactate increased from 3.3 to 18.7 mumol/g of muscle. The correlaiton between the increase in lactate a...

We studied sarcomere performance in single isolated intact frog atrial cells using techniques that allow direct measurement of sarcomere length and force. The purpose of this investigation was to determine whether length-dependent alterations in contractile activation occur in the single isolated cardiac cell. This was accomplished by determining the effect of initial sarcomere length on the ti...

Embryonic myocardium has a high rate of cell proliferation and regulates cellular proliferation, contractile function, and myocardial architecture in response to changes in external mechanical loads. However, the small and complex three-dimensional (3D) structure of the embryonic myocardium limits our ability to directly investigate detailed relationships between mechanical load, contractile fu...

To determine the role of intramitochondrial protein synthesis (PS) and degradation (PD) in contractile activity-induced mitochondrial biogenesis, we evaluated rates of [(35)S]methionine incorporation into protein in isolated rat muscle subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria. Rates of PS ranged from 47 to 125% greater (P < 0.05) in IMF compared with SS mitochondria. Intense...

Microtubules stimulate contractile-ring formation in the equatorial cortex and simultaneously suppress contractility in the polar cortex; how they accomplish these differing activities is incompletely understood. We measured the behavior of GFP-actin in mammalian cells treated with nocodazole under conditions that either completely eliminate microtubules or selectively disassemble astral microt...

The thin filament protein cardiac troponin T (cTnT) is an important regulator of myofilament activation. Here we report a significant change in cardiac energetics in transgenic mice bearing the missense mutation R92Q within the tropomyosin-binding domain of cTnT, a mutation associated with a clinically severe form of familial hypertrophic cardiomyopathy. This functional domain of cTnT has recen...

Cardiovascular disorders continue to constitute major causes of morbidity and mortality in diabetic patients. In this study, the effect of chronic administration of sesame (Sesamum indicum L) seed feeding was studied on aortic reactivity of streptozotocin (STZ)-diabetic rats. Male diabetic rats received sesame seed-mixed food at weight ratios of 3% and 6% for 7 weeks, one week after diabetes in...

Networks and bundles comprised of F-actin and myosin II generate contractile forces used to drive morphogenic processes in both muscle and nonmuscle cells. To elucidate the minimal requirements for contractility and the mechanisms underlying their contractility, model systems reconstituted from a known set of purified proteins in vitro are needed. Here, we describe two experimental protocols ou...

Body movements are mainly provided by mechanical function of skeletal muscle. Skeletal muscle is composed of numerous bundles of myofibers that are sheathed by intramuscular connective tissues. Each myofiber contains many myofibrils that run longitudinally along the length of the myofiber. Myofibrils are the contractile apparatus of muscle and they are composed of repeated contractile units kno...