AIMS Contraction of the heart is regulated by electrically evoked Ca(2+) transients (CaTs). H(+) ions, the end products of metabolism, modulate CaTs through direct interactions with Ca(2+)-handling proteins and via Na(+)-mediated coupling between acid-extruding proteins (e.g. Na(+)/H(+) exchange, NHE1) and Na(+)/Ca(2+) exchange. Restricted H(+) diffusivity in cytoplasm predisposes pH-sensitive ...

Although the Na(+)/K(+) pump is one of the key mechanisms responsible for maintaining cell volume, we have observed experimentally that cell volume remained almost constant during 90 min exposure of guinea pig ventricular myocytes to ouabain. Simulation of this finding using a comprehensive cardiac cell model (Kyoto model incorporating Cl(-) and water fluxes) predicted roles for the plasma memb...

This study was carried out in the Middle Governorate of Gaza Strip, Palestine. The coastal aquifer is the main source of water for domestic, agricultural, and industrial purposes in the study area. During the last three decades the aquifer has deteriorated to a high degree in the quality and quantity due to the over-pumping and the encroachment of seawater.  Hydrogeochemical analysis for ground...

Ion transport and regulation were studied in two, alternatively spliced isoforms of the Na 1 -Ca 2 1 exchanger from Drosophila melanogaster . These exchangers, designated CALX1.1 and CALX1.2, differ by five amino acids in a region where alternative splicing also occurs in the mammalian Na 1 -Ca 2 1 exchanger, NCX1. The CALX isoforms were expressed in Xenopus laevis oocytes and characterized ele...

distribution and mobility of nine mineral elements (k, ca, na, mg, fe, zn, cu, se, and cr) in cultured gentiana rigescens and its root zone soil were determined by atomic absorption spectroscopy. g. rigescens materials were planted under tea and white papaya trees in yun county and yongde of lincang area in yunnan province of china. the results showed that g. rigescens and its soil were high in...

We have used dialyzed squid axons to characterize the ouabain- and bumetanide-insensitive Na efflux components and their relation to the operation of the Na/Ca exchange mechanism. In axons dialyzed with solutions containing nearly physiological concentrations of K, Na, and Mg, three components of the Na efflux can be distinguished: Cai-activated, Cao-dependent Na efflux ("reverse" Na/Ca exchang...

The varanid lizard possesses one of the largest aerobic capacities among reptiles with maximum rates of oxygen consumption that are twice that of other lizards of comparable sizes at the same temperature. To support this aerobic capacity, the varanid heart possesses morphological adaptations that allow the generation of high heart rates and blood pressures. Specializations in excitation-contrac...

Intracellular Ca(2+) ([Ca(2+)](i)) can trigger dual-mode regulation of the voltage gated cardiac sodium channel (Na(V)1.5). The channel components of the Ca(2+) regulatory system are the calmodulin (CaM)-binding IQ motif and the Ca(2+) sensing EF hand-like (EFL) motif in the carboxyl terminus of the channel. Mutations in either motif have been associated with arrhythmogenic changes in expressed...