In response to glucose, mouse beta-cells display slow oscillations of the membrane potential and cytosolic free Ca(2+) concentration ([Ca(2+)](i)), whereas rat beta-cells display a staircase increase in these parameters. Mouse and rat islet cells differ also by their level of Na/Ca exchanger (NCX) activity. The view that the inward current generated by Na/Ca exchange shapes stimulus-induced ele...

We examine theoretically the ability of diffusible cytoplasmic carriers to facilitate delivery of substrate to sites within biological membranes. Two processes are analyzed. In one, delivery of Ca to a site on a membrane surface is examined. As a contrasting example, chelator-supported diffusion to a uniform absorbing surface is considered.

It is unclear that how subcellular organelles respond to external mechanical stimuli. Here, we investigated the molecular mechanisms by which mechanical force regulates Ca(2+) signaling at endoplasmic reticulum (ER) in human mesenchymal stem cells. Without extracellular Ca(2+), ER Ca(2+) release is the source of intracellular Ca(2+) oscillations induced by laser-tweezer-traction at the plasma m...

Gastric acid secretion is dependent on carbonic anhydrase (CA). To define the role of membrane-bound CA, we used biochemical, histochemical, and pharmacological approaches in the frog (Rana pipiens). CA activity and inhibition by membrane-permeant and -impermeant agents were studied in stomach homogenates and microsomal fractions. H(+) secretion in the histamine-stimulated isolated mucosa was m...

Ca(2+) may selectively activate various processes in part by the cell's ability to localize changes in the concentration of the ion to specific subcellular sites. Interestingly, these Ca(2+) signals begin most often at the plasma membrane space so that understanding subplasma membrane signals is central to an appreciation of local signaling. Several experimental procedures have been developed t...

Blend reverse osmosis membranes were fabricated using polyvinyl chloride (PVC) with cellulose acetate (CA) as polymer blends. Tetrahydrofuran (THF) and N-Methyl-2-pyrrolidone (NMP) were used as solvents. The membrane polymer solution was cast on a coated woven fabric support material. The prepared membranes have been characterized by SEM and mechanical properties. SEM r...

Caffeine causes a [Ca]i increase in the cortex of Paramecium cells, followed by spillover with considerable attenuation, into central cell regions. From [Ca]i rest ∼50 to 80 nM, [Ca]i rises within ø3 sec to 500 (trichocyst-free strain tl) or 220 nM (nondischarge strain nd9–28°C) in the cortex. Rapid confocal analysis of wildtype cells (7S) showed only a 2-fold cortical increase within 2 sec, ac...