Rabbits, ages 4-24 weeks, were injected with saline or thyroxine (150 micrograms/kg) for 7 days, and force-velocity curves were generated using papillary muscles from these hearts by a method described previously. In addition, the structure and relative amounts of myosin isozymes from papillary muscles and from 3- to 5-mg segments of the left and right ventricular free wall were analyzed by pol...

Isolated cardiac tissue allows investigators to study mechanisms underlying normal and pathological conditions, which would otherwise be difficult or impossible to perform in vivo. Cultured neonatal rat ventricular cardiac myocytes (NRVM) are widely used to study signaling and growth mechanisms in the heart, primarily due to the versatility, economy, and convenience of this in vitro model. Howe...

In the left ventriculogram in the right anterior oblique projection the plane of the mitral valve is seen in profile and the papillary muscle shadows are outlined. The distance from the middle of the papillary muscles to the plane of the mitral valve during systole was used to assess the average length of the chordae tendineae, and the area of the papillary muscle shadows was measured as an ind...

The chordae tendineae of the heart are collagenous strands which extend from the apical margin of papillary muscles of the heart to the various areas on the ventricular surface of the valve leaflets. They convey the contraction of the papillary muscles to the valve and so prevent the latter’s eversion. Eight hearts of the ostrich were collected, opened the left side of the heart and the length ...

Background—Tumor necrosis factor (TNF)-a has been implicated in the pathogenesis of heart failure and ischemiareperfusion injury. Effects of TNF-a are initiated by membrane receptors coupled to sphingomyelinase signaling and include altered metabolism and calcium cycling, contractile dysfunction, and cell death. We postulate that pressureoverload hypertrophy results in increased myocardial TNF-...

We have examined the pathophysiological role of readmission of oxygen (and hence production of oxygen-derived free radicals) in the initiation of reperfusion-induced arrhythmias by separating, on a temporal basis, readmission flow from readmission of oxygen. Isolated rat hearts (n = 12/group) were subjected to 10 minutes of regional ischemia and 10 minutes of reperfusion. In controls reperfused...

abstract the effect of different larval density of chilo suppressalis walker was evaluated through 2006-2008 on rice infestation in controlled condition of the cages. the results indicated that there were significant effects between dead hearts, white heads and crop yield. the highest dead hearts and white heads were related to the treatment of 32 larvae per m2 and the lowest ones were obtained...

The nature of digitoxin fixation in isolated hearts was studied with C14 labelled digitoxin. Fixation wvas greatest in the early stages of perfusion. The amount of drug fixed was measured directly. A considerable percentage cf the digitoxin in cardiac muscle was changed to other substances. These substances are more firmly bound to the heart than digitoxin. T HE preparation of pure, randomly la...

Premenopausal females have a lower incidence of cardiovascular disease than their male counterparts, but the mechanism is unclear. Estrogen has been thought to signal through two nuclear receptors: estrogen receptor-alpha or estrogen receptor-beta; however, a third, membrane-bound receptor G protein-coupled estrogen receptor (GPER), has been identified and shown to bind estrogen with high affin...

1. The effect of the adenosine A(2) receptor (AdoA(2)R) agonist N(6)-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (DPMA) on adenosine A(1) receptor (AdoA(1)R)-mediated negative inotropic responses was investigated in rat heart. 2. Hearts from male Wistar rats (250-350 g) were perfused with Krebs'-Henseleit solution at constant flow in non-recirculating Langendorff mode. Hearts we...