The membrane potential in the dark and the saturated response height of the ventral nerve photoreceptor of Limulus was measured by an intracellular electrode while the external concentra­ tion of calcium, magnesium and sodium ions was varied. Decreasing the extracellular calcium concentration from 10-2 mol/1 causes a calcium-dependent lowering of the dark membrane potential and at very low conc...

A perfused rainbow trout heart was developed which generated its own intrinsic heart rate and a physiological power output. This preparation was used to examine the intrinsic mechanical properties of the trout heart, the dose-response effects of catecholamines and extracellular calcium on these properties, and the effects of catecholamines and extracellular calcium during exposure to acidotic c...

N-n-butyl haloperidol iodide (F2) has been shown to antagonize myocardial ischemia/reperfusion injury by blocking calcium channels. This study explores the biological functions of ERK pathway in cardiomyocytes hypoxia/reoxygenation injury and clarifies the mechanisms by which F2 ameliorates cardiomyocytes hypoxia/reoxygenation injury through the extracellular-calcium-dependent and -independent ...

The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mech...

Calcium homeostasis in the extracellular fluid is tightly controlled and defended physiologically. Hypercalcemia always represents considerable underlying pathology and occurs when the hormonal control of calcium homeostasis is overwhelmed. The major hormones that are responsible for normal calcium homeostasis are parathyroid hormone and 1,25-dihydroxyvitamin D; these hormones control extracell...

The kidney handles calcium by filtration and reabsorption. About 60% of the plasma calcium is filterable, and 99% is reabsorbed in the tubule. In the proximal tubule, the reabsorption is passive and paracellular, but in the distal tubule is active and transcellular. Thus, renal tubular cells are exposed to very high concentrations of calcium in both, the extracellular and the intracellular comp...

In the epidermis, one of the earliest characterized events in keratinocyte differentiation is the coordinate induction of a pair of keratins specifically expressed in suprabasal cells, keratin 1 (K1) and keratin 10 (K10). Both in vivo and in vitro, extracellular calcium is necessary for several biochemical and structural changes during keratinocyte differentiation. However, it has been unclear ...

Extracellular calcium concentration changes in the CA1 of the hippocampus during burst activity were measured during postischemic reflow, and the involvement of N-methyl-D-aspartate (NMDA) receptors was evaluated. In adult Wistar rats global ischemia was induced by four-vessel occlusion for 20 min. After 6 h of postischemic reflow, the animals were halothane-anesthetized and reintubated. A doub...

Recently we showed that staurosporine uses the extracellular calcium ions to affect on neurite outgrowth in PC12 cells. However, these mechanisms during staurosporine-induced cell death are still unclear. In this study, we investigated the relation between of reactive oxygen species (ROS) and extracellular calcium entry during staurosporine-induced cell death in PC12 cells. The results showed t...