geoscience.net logo
+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Tetrodotoxin-blockable calcium currents in rat ventricular myocytes; a third type of cardiac cell sodium current


, : Tetrodotoxin-blockable calcium currents in rat ventricular myocytes; a third type of cardiac cell sodium current. Journal of Physiology (Cambridge) 505(2): 353-369, Dec 1

1. Whole-cell patch clamp currents from freshly isolated adult rat ventricular cells, recorded in external Ca2+ (Cao2+) but no external Na+ (Nao+), displayed two inward current components: a smaller component that activated over more negative potentials and a larger component (L-type Ca2+ current) that activated at more positive potentials. The smaller component was not generated by Ca2+ channels. It was insensitive to 50 muM Ni2+ and 10 muM La3+, but suppressed by 10 muM tetrodotoxin (TTX). We refer to this component as ICa(TTX). 2. The conductance-voltage, g(V), relation in Cao2+ only was well described by a single Boltzmann function (half-maximum potential, V1/2, of -44.5; slope factor, k, of -4.49 mV, means of 3 cells). g(V) in Cao2+ plus Neo was better described as the sum of two Boltzmann functions, one nearly identical to that in Cao2+ only (mean V1/2 of -45.1 and k of -3.90 mV), and one clearly distinct (mean V1/2 of -35.6 and k of -2.31 mV). Mean maximum conductance for ICa(TTX) channels increased 23.7% on adding 1 mM Nao+ to 3 mM Cao2+. ICa(TTX) channels are permeable to Na+ ions, insensitive to Ni2+ and La3+ and blocked by TTX. They are Na+ channels. 3. ICa(TTX) channels axe distinct from classical cardiac Na+ channels. They activate and inactivate over a more negative range of potentials and have a slower time constant of inactivation than the classical Na+ channels. They are also distinct from yet another rat ventricular Na+ current component characterized by a much higher TTX sensitivity and by a persistent, non-fast-inactivating fraction. That ICa(TTX) channels activate over a more negative range of potentials than classical cardiac Na+ channels suggests that they may be critical for triggering the ventricular action potential and so of importance for cardiac arrhythmias.

US$19.90

DOI: 10.1111/j.1469-7793.1997.353bb.x


Other references

Zaidi, M.; Alam, A.S.M.T.; Huang, C.L.H.; Pazianas, M.; Bax, C.M.R.; Bax, B.E.; Moonga, B.S.; Bevis, P.J.R.; Shankar, V.S., 1993: Extracellular calcium sensing by the osteoclast. An increasing number of cell types appear to detect changes in the extracellular Ca-2+ concentration and accordingly modify their function. We review recent evidence for the existence and function of such a mechanism in the osteoclast. Elevated ex...

Arslan, Nimet, 1959: The effect of pH on water-permeability in living plant cells. The purpose of this research is to investigate the cause of the contradictory results obtained in the literature for the effect of varying pH concentrations of the medium on the rate of water permeability of the upper epidermis cells of AIlium cep...

Pellicer, A.; Wigler, M.; Axel, R.; Silverstein, S., 1978: The transfer and stable integration of the HSV thymidine kinase gene into mouse cells. Treatment of mutant mouse cells (Ltk-) deficient in thymidine kinase with Bam I restriction endonuclease-cleaved HSV-1 DNA results in the appearance of numerous surviving colonies which stably express thte tk+ phenotype. Through a series of electr...

Carroll, Robert L., 1997: Mesozoic marine reptiles as models of long-term, large-scale evolutionary phenomena. Unknown

Kwok, T.; Tang, C.; Woo, J.; Lai, W.K.; Law, L.K.; Pang, C.P., 1998: Randomized trial of the effect of supplementation on the cognitive function of older people with subnormal cobalamin levels. Background. Low serum cobalamin levels are often found in apparently normal older subjects. A major worry of leaving cobalamin deficiency untreated is that it may lead to subtle deterioration in cognitive function. Objectives. To investigate the e...

Cardoso, Joao-Luis, 1996: The large Upper-Pleistocene mammals in Portugal. A synthetical approach. This study presents a review of the large-sized mammals from the Upper Pleistocene of Portugal, excluding Mustelids. Following the study of the materials kept in the Servicos Geologicos de Portugal and from other Institutions, as well as from site...

Choi, W.; Lowder, M.W.; Ferreira, F.; Swaab, T.Y.; Henderson, J.M., 2017: Effects of word predictability and preview lexicality on eye movements during reading: A comparison between young and older adults. Previous eye-tracking research has characterized older adults' reading patterns as "risky," arguing that compared to young adults, older adults skip more words, have longer saccades, and are more likely to regress to previous portio...

Drachev, L.A.; Kaulen, A.D.; Komrakov, A.Y., 1994: The nature of the multicomponent M-intermediate formation in the bacteriorhodopsin photocycle. III. A kinetic analysis of the azide effect on the D96N bacteriorhodopsin photocycle. The M-intermediate formation in D96N bacteriorhodopsin is fitted well by a sum of three components having tau-1 = 55 mu-s, tau-2 = 220 mu-s and t-3 = 1 ms (pH 7.0, 20 degree C). The same components are present in the L-intermediate decay. The azid...

Pina, R.; Romeo, I.; Ortega, L.; Lunar, R.; Capote, R.; Gervilla, F.; Tejero, R.; Quesada, C., 2010: Origin and emplacement of the Aguablanca magmatic Ni-Cu-PGE sulfide deposit, SW Iberia; a multidisciplinary approach. A model is proposed for the origin and emplacement of the ca. 341 Ma Aguablanca magmatic Ni-Cu-(platinum group element [PGE]) sulfide deposit (SW Iberia) integrating petrological, geochemical, structural, and geophysical data. The Aguablanca depos...

Klenova, A.V.; Borodina, N.P.; Shevlyagin, V.Y., 1987: Release of polyoma virus from human transformed cells. Virus reproduction and activation were studied in human cells transformed with human polyoma virus. At the stage of spontaneous viral production, such methods of activation as somatic hybridization and DNA transfection were successful. Special met...