The rate of Ca influx into ghosts containing arsenazo III changes with time, being most rapid during the first 5 min after Ca is added to the outside and declining thereafter. The rate of Ca influx is a nonlinear function ofextracellular Ca and plateaus as the latter is increased above 1 mM. The rate of Ca influx was measured as a function of the transmembrane gradients of Na and K and changes ...

Elevation of intracellular calcium ion (Ca(2+)) levels is a vital event that regulates T lymphocyte homeostasis, activation, proliferation, differentiation, and apoptosis. The mechanisms that regulate intracellular Ca(2+) signaling in lymphocytes involve tightly controlled concinnity of multiple ion channels, membrane receptors, and signaling molecules. T cell receptor (TCR) engagement results ...

We hypothesized that the requirement for Ca(2+)-dependent exocytosis in cell-membrane repair is to provide an adequate lowering of membrane tension to permit membrane resealing. We used laser tweezers to form membrane tethers and measured the force of those tethers to estimate the membrane tension of Swiss 3T3 fibroblasts after membrane disruption and during resealing. These measurements show t...

A theory is presented according to which the neuronal membrane and synapses are influenced by membrane-bound S100 protein and a membrane-associated network of actin-like, 20-A-diameter, coiled filaments and the competition by both proteins for Ca(2+). The discussion is based on observations made with fluorescein- and peroxidase-conjugated antiserum against S100 protein on isolated nerve cells. ...

We have investigated the effects of natriuretic peptides on oscillations in [Ca(2+)](c) (cytosolic free Ca(2+) concentration) in two different cell types: freshly isolated rat hepatocytes and the ECV304 cell line. Our data, from both cell types, suggest that natriuretic peptides modulate the frequency of [Ca(2+)](c) oscillations through alterations in plasma membrane Ca(2+) fluxes. Here, we rev...

Prolactin (PRL) is involved in numerous biological processes in peripheral tissues and the brain. Although numerous studies have been conducted to elucidate the signal transduction pathways associated with the PRL receptor, very few have examined the role of ion conductances in PRL actions. We used the patch-clamp technique in "whole cell" configuration and microspectrofluorimetry to investigat...

Polyamines regulate a variety of cation and K(+) channels, but their potential effects on cation-transporting ATPases are underexplored. In this work, noninvasive microelectrode ion flux estimation and conventional microelectrode techniques were applied to study the effects of polyamines on Ca(2+) and H(+) transport and membrane potential in pea roots. Externally applied spermine or putrescine ...

BACKGROUND The mechanical, rheological and shape properties of red blood cells are determined by their cortical cytoskeleton, evolutionarily optimized to provide the dynamic deformability required for flow through capillaries much narrower than the cell's diameter. The shear stress induced by such flow, as well as the local membrane deformations generated in certain pathological conditions, suc...

this experiment was conducted to evaluate the effects of salt stress on some agro-physiological traits in ten varieties of bread (triticum aestivum l.) and durum (triticum turgidum l.) wheats in seedling stage. a greenhouse experiment was carried out as a split plot experiment based on a completely randomized design with four replications in hydroponic condition. different agronomic and physiol...

Vascular tone and hence blood pressure are determined by the contractile state of vascular smooth muscle cells (VSMCs) within the blood vessel wall, which is regulated by intracellular calcium concentration ([Ca]i). Vasoconstrictors act through increasing [Ca]i as well as on the apparent calcium sensitivity of the contractile process in VSMCs, whereas relaxing factors have the opposite effect. ...