BACKGROUND Atrial fibrillation (AF) is the most common arrhythmia in humans, yet; treatment has remained sub-optimal due to poor understanding of the underlying mechanisms. Cardiac alternans precede AF episodes, suggesting an important arrhythmia substrate. Recently, we demonstrated ventricular SERCA2a overexpression suppresses cardiac alternans and arrhythmias. Therefore, we hypothesized that ...

Bradykinin (BK)-induced changes in intracellular calcium level ([Ca2+]i) were studied on fura 2-loaded afferent (AA) and efferent glomerular arterioles (EA) microdissected from juxtamedullary renal cortex. A distinction was made between thin and muscular EA. In AA and both types of EA, BK increased [Ca2+]ithrough activation of B2 receptors located only on the endothelium. The responses were not...

The relationship between extracellular Ca2+ concentration and EPSC amplitude was investigated at excitatory autapses on cultured hippocampal neurons. This relationship was steeply nonlinear, implicating the cooperative involvement of several Ca2+ ions in the release of each vesicle of transmitter. The cooperativity was estimated to be 3.1 using a power function fit and 3.3 using a Hill equation...

introduction: since organophosphorus compounds (op) are toxic and designed to destroy insects and pest species, there are many hazards associated with their use. although, the main target site of these compounds is acetylcholinesterase (ache), however it has become increasingly evident that ops have also other direct effects on cellular processes. in the present study, the effects of low concen...

background: the predominant phytoestrogen in soy and derived products is the isoflavone genistein. genistein has antioxidant properties. morphine is a main psychoactive chemical in opium that can increase the generation of free radicals and therefore it could adversely affects the spermatogenesis. objective: the main goal was to investigate whether the genistein could protect morphine adverse e...

Background: Oocyte maturation is usually defined as the period of progression from the first to the second meiotic arrest and involves coordinated nuclear and cytoplasmic modification. Ca2+ signals are known as important regulators of oocyte maturation. Extracellular Ca2+ is important for first polar body formation, normal meiosis kinetics, and for preserving the chromosome and spindle configur...

Calcitriol acts via its receptor (VDR) and inhibits PTH secretion and parathyroid cell proliferation. Increased prevalence of the polymorphic VDR alleles b, a, and T has been demonstrated in sporadic primary hyperparathyroidism. Sixty-two patients with primary hyperparathyroidism due to parathyroid adenoma (mean age, 69.5 +/- 1.4 yr) were genotyped for these VDR polymorphisms. Dispersed cells o...

Block of Na/Ca exchange (NCX) has potential therapeutic applications, in particular, if a mode-selective block could be achieved, but also carries serious risks for disturbing the normal Ca2+ balance maintained by NCX. We have examined the effects of partial inhibition of NCX by SEA-0400 (1 or 0.3 micromol/L) in left ventricular myocytes from healthy pigs or mice and from mice with heart failur...

Steady-state free Ca2+ concentrations have been measured with a Ca2+ electrode using suspensions of isolated rat liver mitochondria or saponin-treated hepatocytes. Mitochondria, when incubated in the presence of Mg2+ and MgATP2-, maintain a steady-state PCB2+ (-log [Ca2+]) of approximately 6.1 (0.8 FM). Addition of spermine lowered this value to a pCa2+ of 6.6 (0.25 pM). Spermine was the most...