Cerebellar Purkinje neurons demonstrate a form of synaptic plasticity that, in acutely prepared brain slices, has been shown to require calcium release from the intracellular calcium stores through inositol trisphosphate (InsP(3)) receptors. Similar studies performed in cultured Purkinje cells, however, find little evidence for the involvement of InsP(3) receptors. To address this discrepancy, ...

Gap junctional conductance (gj) between cardiac ventricular myocyte pairs is rapidly, substantially, and reversibly reduced by sarcoplasmic acidification with CO2 when extracellular calcium activity is near physiological levels (1.0 mM CaCl2 added; 470 microM Ca++). Intracellular calcium concentration (Cai), measured by fura-2 fluorescence in cell suspensions, was 148 +/- 39 nM (+/- SEM, n = 6)...

Somatostatin is a neurohormone peptide that inhibits a variety of secretory responses in different cell types. We have investigated the effects of somatostatin on calcium current and intracellular free calcium in AtT-20 cells, a pituitary tumor line in which the inhibitory actions of this peptide have been well characterized. At concentrations similar to those that inhibit adrenocorticotropic h...

Cyclooxygenase (COX)-1 and hematopoietic prostaglandin (PG) D synthase (H-PGDS) proteins, which are both involved in the arachidonate cascade, were stable in human megakaryocytic MEG-01 cells. In contrast, once the intracellular calcium level was increased by treatment with a calcium ionophore, both protein levels rapidly decreased with a half-life of less than 30 and 120 min for COX-1 and H-PG...

Bruton's tyrosine kinase (Btk) is essential for B-lineage development and represents an emerging family of non-receptor tyrosine kinases implicated in signal transduction events initiated by a range of cell surface receptors. Increased dosage of Btk in normal B cells resulted in a striking enhancement of extracellular calcium influx following B-cell antigen receptor (BCR) cross-linking. Ectopic...

BACKGROUND Calcium and magnesium ions play a key role in the physiology of muscular contraction: changes in calcium ions concentration may be involved in the pathogenesis of fibromyalgia. Since the plasmatic levels of calcium and magnesium in fibromyalgia patients is always in the normal range, it seemed interesting to evaluate the intracellular calcium and magnesium concentration. METHODS Th...

Trypanosoma cruzi, the protozoan responsible for Chagas disease, employs distinct strategies to invade mammalian host cells. In the present work we investigated the participation of calcium ions on the invasion process using primary cultures of embryonic mice cardiomyocytes which exhibit spontaneous contraction in vitro. Using Fura 2-AM we found that T. cruzi was able to induce a sustained incr...

The fluorescent indicator fura-2 was used to measure cytoplasmic calcium in presynaptic terminals in the crayfish Procambarus clarkii under conditions that raise intracellular sodium to examine whether sodium can elevate intracellular calcium concentration ([Ca2+]i) or prolong its efflux and thus influence the magnitude and duration of posttetanic potentiation (PTP). Sodium was elevated in pres...

This study examines the regulation of cGMP by illumination and by calcium during signal transduction in vertebrate retinal photoreceptor cells. We employed an electropermeabilized rod outer segment (EP-ROS) preparation which permits perfusion of low molecular weight compounds into the cytosol while retaining many of the features of physiologically competent, intact rod outer segments (ROS). Whe...