Current-clamp recordings were made from the primary (1°) and secondary (2°) branching points (BPs) of axons at the crayfish neuromuscular junction. Action potential (AP) firing initiated by current injected at the 2° BP showed strong adaptation or high-frequency firing at threshold current, whereas AP firing frequency at the 1° BP exhibited a gradual rise with increasing current amplitude. The ...

Recently, the influence of thermal processes on electrophysiology has clearly been underlined by Bini et al. [2], using a FitzHugh–Nagumo-type (FHN-type) model. When the temperature is raised, the action potential duration (APD) has been shown to shorten, while the action potential (AP) amplitude decreases, and the conduction velocity increases [2]. In the present study, we investigate the effe...

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 potential (AP) myocytes and the rat atrial (RA) model exemplifying myocytes with short APs. The interventions were activation of stretch-gated cationic channels, increase of intracellular Na+ concentration ([Na+]i), simulated bet-adrenoce...

Vecchietti S, Grandi E, Severi S, Rivolta I, Napolitano C, Priori SG, Cavalcanti S. In silico assessment of Y1795C and Y1795H SCN5A mutations: implication for inherited arrhythmogenic syndromes. Am J Physiol Heart Circ Physiol 292: H56–H65, 2007. First published September 15, 2006; doi:10.1152/ajpheart.00270.2006.—The effects of two SCN5A mutations (Y1795C, Y1795H), previously identified in one...

Action potential (AP) generation and propagation through the dendritic tree of pyramidal neurons has received much attention lately1. Experiments indicate that inhibitory postsynaptic potentials (IPSPs) have a decisive e ect in controlling action potential invasion in dendrites2, 3. However, these phenomena were observed in slices, and remain to be investigated under in vivo conditions where ne...

Mudpuppy parasympathetic neurons exhibit spontaneous miniature hyperpolarizations (SMHs) that are generated by potassium currents, which are spontaneous miniature outward currents (SMOCs), flowing through clusters of large conductance voltage- and calcium (Ca(2+))-activated potassium (BK) channels. The underlying SMOCs are initiated by a Ca(2+)-induced Ca(2+) release (CICR) mechanism. Perforate...

The initial stages of diabetic nephropathy are characterized, in part, by expansion of the mesangial matrix and thickening of the glomerular basement membrane which are caused by increased extracellular matrix (ECM) protein synthesis and reduced degradation, a consequence of decreased matrix metalloproteinase (MMP) activity. These changes have been largely attributed to the effects of hyperglyc...

I(D) is a slowly inactivating 4-aminopyridine (4-AP)-sensitive potassium current of hippocampal pyramidal neurons and other CNS neurons. Although I(D) exerts multifaceted influence on CNS excitability, whether I(D) is subject to modulation by neurotransmitters or neurohormones has not been clear. We report here that one prominent effect of metabotropic glutamate receptor (mGluR) activation by s...

A comparison of results of modelling and physiological experiments allowed to estimate in the first approximation the quantitative contribution of calcium and sodium ions to the generation of different ionic currents determining the shape of the action potential (AP). Generally, the model reproduced adequately variations in AP shape with changes in the external concentrations of Na+ and Ca2+. A...

Action potential (AP) propagation in myelinated nerves requires clustered voltage gated sodium and potassium channels. These channels must be specifically localized to nodes of Ranvier where the AP is regenerated. Several mechanisms have evolved to facilitate and ensure the correct assembly and stabilization of these essential axonal domains. This review highlights the current understanding of ...