The purpose of this study was to investigate sex differences in the functional response of isolated rat heart ventricular myocytes to beta-adrenergic stimulation and in isoproterenol-stimulated signal transduction. Fractional shortening was measured using a video edge-detection system in control- and isoproterenol-stimulated myocytes that had been isolated from weight-matched rats. Number and a...

We investigated the molecular mechanism underlying the processing of pro-B-type natriuretic peptide (proBNP). Rat neonatal atrial and ventricular myocytes were cultured separately. We examined the molecular forms of secreted and intracellular BNP in atrial and ventricular myocytes; levels of corin and furin mRNA in atrial and ventricular myocytes; the effect their knockdown on proBNP processing...

In a heart with hypertrophic cardiomyopathy without asymmetrical septal hypertrophy the number of transmural myocytes, the mean size of myocytes, and the percentage area of interstitial space were similar in the ventricular septum and left ventricular posterior wall, whereas in a reported series of 14 hearts with hypertrophic cardiomyopathy with asymmetrical septal hypertrophy the number of tra...

In the present work, we found that the delayed rectifying outward potassium current (I(K)) in adult and neonatal cat ventricular myocytes consists of both rapid and slow components, I(Kr) and I(Ks), respectively, which can be isolated pharmacologically. Thus after complete blockade of I(Kr) with dofetilide, the remaining I(Ks) current is homogeneous, as shown by an envelope of tails test. I(Kr)...

Methods and Results: 40 mol/L H2O2 significantly increased CaMKII oxidation and autophosphorylation in permeabilized rabbit cardiomyocytes. Without free [Ca]i (5 mmol/L BAPTA/1 mmol/L Br2-BAPTA) or after SR depletion (caffeine 10 mmol/L, thapsigargin 5 mol/L), the H2O2-dependent CaMKII oxidation and autophosphorylation was abolished. H2O2 significantly increased SR Ca spark frequency (confocal ...

TRPV4 protein forms a Ca2+-permeable channel that is sensitive to osmotic and mechanical stimuli and responds to warm temperatures, and expresses widely in various kinds of tissues. As for cardiac myocytes, TRPV4 has been detected only at the mRNA level and there were few reports about subcellular localization of the protein. The purpose of the present study was to investigate the expression pr...

Cooperative gating of localized ion channels ranges from fine-tuning excitation–contraction coupling in muscle cells to controlling pace-making activity the heart. Membrane deformation resulting contraction activates stretch-activated (SA) cation channels. The subsequent Ca 2+ influx spatially -sensitive K + fine-tune spontaneous contraction. To characterize endogenously expressed intermediate ...

Macrophages are found in the heart as part of the inflammatory response. To determine whether macrophages could contribute to myocardial dysfunction, rat ventricular myocytes were isolated and cocultured with elicited peritoneal macrophages in media containing tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, or endotoxin for 4 h. Cardiac myocytes were electrically stimulated, and fractiona...

The transfection of cardiac myocytes is difficult, and so most of the data regarding the regulation of trafficking and targeting of cardiac ion channels have been obtained using heterologous expression systems. Here we apply the fast biolistic transfection procedure to adult cardiomyocytes to show that biolistically introduced exogenous voltage-gated potassium channel, Kv1.5, is functional and,...

Vascular endothelial growth factor (VEGF) has been proposed to be among the candidate factors with the most potential to play a role in ischemia-induced collateral vessel formation. Recently, we found that VEGF activated the mitogen-activated protein kinase cascade in cultured rat cardiac myocytes. To elucidate how VEGF affects adhesive interaction of cardiac myocytes with the extracellular mat...