BACKGROUND Myocytes from failing hearts produce slower and smaller Ca(2+) transients associated with reduction in expression of sarcoplasmic reticulum (SR) Ca(2+) ATPase and an overexpression of Na(+)/Ca(2+) exchanger. Since the physiological role of both these proteins is competing for, and removing, Ca(2+) from the cytoplasm, overexpression of the exchanger may compensate for less effective S...

It has been hypothesized, based on physiological evidence, that there is a greater proportion of 1-adrenergic receptors on the myocytes of the conduction system when compared with the working myocardium. The purpose of these studies was to examine f3-adrenergic receptor subtype in the conduction system of the dog by using the technique of coverslip autoradiography. Scintillation studies of ['25...

The kinetics of contractions and Ca(2+) transients are slowed in myocytes from failing hearts. The mechanisms accounting for these abnormalities remain unclear. Myocardial infarction (MI) was produced by ligation of the circumflex artery in rabbits. We used confocal microscopy to record spatially resolved Ca(2+) transients during field stimulation in left ventricular (LV) myocytes from control ...

Transient receptor potential melastatin member 4 (TRPM4) encodes a Ca2+-activated, non-selective cation channel that is functionally expressed in several tissues, including the heart. Pathogenic mutants TRPM4 have been reported patients with inherited cardiac diseases, conduction blockage and Brugada syndrome. Heterologous expression of mutant channels cell lines indicates these mutations can l...

Cultures were prepared of embryonic cells from Drosophila melanogaster. Neurons and myocytes differentiated in vitro from their respective stem cells. Electron microscopy showed that neuromuscular junctions formed where axons contacted myocytes. Electrical stimuli were applied to axons and these caused contractions of innervated myocytes. This is the first report of insect or other invertebrate...

Cardiac myocytes originating from different parts of the heart exhibit varying morphology and ultrastructure. However, the difference in their dynamic behavior is unclear. We examined the contraction of cardiac myocytes originating from the apex, ventricle, and atrium, and found that their dynamic behavior, such as amplitude and frequency of contraction, differs depending on the heart segment o...

Paraquat (PQ) is a highly lethal herbicide. Ingestion of large quantities PQ usually results in cardiovascular collapse and eventual mortality. Recent pieces evidence indicate possible involvement oxidative stress- inflammation-related factors PQ-induced cardiac toxicity. However, little information exists on the relationship between hemodynamic electromechanical effects involved acute poisonin...

UNLABELLED Prolongation of the Ca2+ transient and action potential (AP) durations are two characteristic changes in myocyte physiology in the failing human heart. The hypothesis of this study is that Ca2+ influx via reverse mode Na+/Ca2+ exchanger (NCX) or via L-type Ca2+ channels directly activates contraction in failing human myocytes while in normal myocytes this Ca2+ is transported into the...

We measured [Ca]i and [Na ]i in isolated transgenic (TG) mouse myocytes overexpressing the Na -Ca exchanger and in wild-type (WT) myocytes. In TG myocytes, the peak systolic level and amplitude of electrically stimulated (ES) [Ca]i transients (0.25 Hz) were not significantly different from those in WT myocytes, but the time to peak [Ca]i was significantly prolonged. The decline of ES [Ca]i tran...