Han, Chunlei, Pasi Tavi, and Matti Weckström. Modulation of action potential by [Ca2 ]i in modeled rat atrial and guinea pig ventricular myocytes. Am J Physiol Heart Circ Physiol 282: H1047–H1054, 2002; 10.1152/ajpheart.00573. 2001.—We simulated mechanisms that increase Ca2 transients with two models: the Luo-Rudy II model for guinea pig (GP) ventricle (GP model) representing long action potent...

There are several types of nerve cells in the central nervous system. Thanks to synaptic connections, these form large and complicated networks. However, have a stereotypical electrical activity called action potential (AP) or spike. In this work, mechanisms formation typical signal methods transferring from one cell another were investigated using Hodgkin-Huxley neuron model simulations. It ha...

Action Potential (APs) patterns of sensory cortex neurons encode a variety of stimulus features, but how can a neuron change the feature to which it responds? Here, we show that in vivo a spike-timing-dependent plasticity (STDP) protocol-consisting of pairing a postsynaptic AP with visually driven presynaptic inputs-modifies a neurons' AP-response in a bidirectional way that depends on the rela...

OBJECTIVES The aim of the present study was to assess and compare the dynamics of L-type Ca(2+) current (I(Ca,L)) during physiologic action potential (AP) in canine ventricular cardiomyocytes of epicardial (EPI) and endocardial (ENDO) origin. METHODS I(Ca,L) was recorded on cells derived from the two regions of the heart using both AP voltage clamp and conventional whole cell voltage clamp te...

An analysis of Sox9 binding profiles in developing chondrocytes identified marked enrichment of an AP-1-like motif. Here, we have explored the functional interplay between Sox9 and AP-1 in mammalian chondrocyte development. Among AP-1 family members, Jun and Fosl2 were highly expressed within prehypertrophic and early hypertrophic chondrocytes. Chromatin immunoprecipitation followed by DNA sequ...

In this study, a novel mesoporous silica nanoparticles drug carrier contributes to improving the solubility, dissolution, and the oral bioavailability of apigenin (AP). The apigenin of solid dispersion of mesoporous silica nanoparticles (AP-MSN) was prepared by physical absorption method and also, in-vitro drug release and in-vivo bioavailability performance were evaluated. Based on its solubil...

Background. The primary mechanism of tissue injury by radiofrequency catheter ablation is presumed to be thermally mediated. However, the myocardial cellular electrophysiological effects of hyperthermia are not well characterized. We used an in vitro model of isolated guinea pig right ventricular papillary muscle to investigate the acute cellular electrophysiological effects of hyperthermia. Me...

Real-time mapping and manipulation of electrophysiology in three-dimensional (3D) tissues could have important impacts on fundamental scientific and clinical studies, yet realization is hampered by a lack of effective methods. Here we introduce tissue-scaffold-mimicking 3D nanoelectronic arrays consisting of 64 addressable devices with subcellular dimensions and a submillisecond temporal resolu...

The cardiac action potential (AP) and the consequent cytosolic Ca(2+) transient are key indicators of cardiac function. Natural developmental processes, as well as many drugs and pathologies change the waveform, propagation, or variability (between cells or over time) of these parameters. Here we apply a genetically encoded dual-function calcium and voltage reporter (CaViar) to study the develo...

BACKGROUND The early phase of action potential (AP) repolarization is critical to impulse conduction in the heart because it provides current for charging electrically coupled cells. In the present study we tested the impact of heart failure-associated electrical remodeling on AP propagation. METHODS AND RESULTS Subepicardial, midmyocardial, and subendocardial myocytes were enzymatically diss...