High resistance epithelia express on their apical side an amiloride-sensitive sodium channel that controls sodium reabsorption. A cDNA was found to encode a 1,420-amino acid long polypeptide with no signal sequence, a putative transmembrane segment, and three predicted amphipathic alpha helices. A corresponding 5.2-kb mRNA was detected in Xenopus laevis kidney, intestine, and oocytes, with weak...

Amiloride-sensitive epithelial sodium channels constitute the rate-limiting step for sodium reabsorption in the distal part of the renal tubule, in the distal colon, in the ducts of several exocrine glands, and in the airways (Rossier et al., 1994). Until recently, the classification of the epithelial sodium channels was exclusively based on biophysical and pharmacological properties: sodium an...

Persistent sodium channel activity modulates neuronal gain in a neurotransmitter-dependent fashion. Previous studies have suggested that persistent and spike-related sodium channel activities are mediated by separate species. In this issue of Neuron, Taddese and Bean (2002) show that a single channel population is sufficient to explain both gating behaviors. A simple allosteric model is provide...

Automatic neuron firing is an important and interesting research subject in neuroelectrophysiology. Through the original Hodgkin-Huxley model, we investigate its codimension 1 bifurcations along maximum conductance of the sodium channel, maximum conductance of potassium channel, and extracellular potassium concentration. We find that increasing maximum conductance of sodium channel, or decreasi...

RNA blot hybridization analyses using probes specific for sodium channels I, II and III revealed high levels of sodium channel I mRNA and low levels of sodium channel II and III mRNAs in peripheral nervous system (PNS) tissues. The developmental expression patterns of these mRNAs were generally similar to those described for the central nervous system. The small amounts of sodium channel I and ...

Sodium channels are central to a host of fundamental cellular processes, including sensory perception, pain, and muscle contraction. In order to understand any of these processes in detail, it is necessary to know the atomic structure of the channel proteins both with and without bound sodium ions. In this issue, Naylor et al (2016) present the structure of a bacterial sodium channel tetramer. ...

STRUCTURE AND FUNCTION OF SODIUM CHANNEL SUBUNITS .. . . . . . . . . . 495 Purification and Characterization ....... , . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . 495 Cloning and Primary Structure of the Sodium Channel a Subunit. . . . . . . . . . . . . . . 496 Cloning and Primary Structure of the {Jl and {32 Subunits. . . . . . . . . . . . . . . . . . . . . 498 Functional R...

47 J Cardiovasc. Dis. Res. Vol. 1 / No 2 in 1996,[4] the identifi cation of mutations and investigation of genotype-phenotype relationships of channelopathies have become focal points in the fi eld of genetics and cardiology. For Brugada syndrome alone, 7 related genes, and hundreds of associated mutations have been identifi ed.[5,6] SCN5A, encoding the Nav1.5 α-subunit, causes the sodium ion c...

Non-dystrophic myotonias are rare diseases caused by mutations in skeletal muscle chloride and sodium ion channels with considerable phenotypic overlap between diseases. Few prospective studies have evaluated the sensitivity of symptoms and signs of myotonia in a large cohort of patients. We performed a prospective observational study of 95 participants with definite or clinically suspected non...