Endoplasmic reticulum (ER) Ca2+ refilling is an active process to ensure an appropriate ER Ca2+ content under basal conditions and to maintain or restore ER Ca2+ concentration during/after cell stimulation. The mechanisms to achieve successful ER Ca2+ refilling are multiple and built on a concerted action of processes that provide a suitable reservoir for Ca2+ sequestration into the ER. Despite...

The concerted action of inositol 1,4,5-trisphosphate (IP3) and Ca2+ on the IP3 receptor Ca2+ release channel (IP3R) is a fundamental step in the generation of cytosolic Ca2+ oscillations and waves, which underlie Ca2+ signaling in many cells. Mitochondria appear in close association with regions of endoplasmic reticulum (ER) enriched in IP3R and are particularly responsive to IP3-induced increa...

Bovine chromaffin secretory vesicle ghosts loaded with Na+ were found to take up Ca2+ when incubated in K+ media or in sucrose media containing micromolar concentrations of free Ca2+. Li+- or choline+-loaded ghosts did not take up Ca2+. The Ca2+ accumulated by Na+-loaded ghosts could be released by the Ca2+ ionophore A23187, but not by EGTA. Ca2+ uptake was inhibited by external Sr2+, Na+, Li+,...

Spontaneous, localized intracellular Ca2+concentration ([Ca2+]i) transients (Ca2+ sparks) in skeletal, cardiac, and smooth muscle cells are thought to represent Ca2+ release through ryanodine-receptor (RyR) channels. In porcine tracheal smooth muscle (TSM) cells, ACh induces propagating [Ca2+]ioscillations that also represent Ca2+ release through RyR channels. We used real-time confocal imaging...

We have used digital fluorescence imaging techniques to explore the interplay between mitochondrial Ca2+ uptake and physiological Ca2+ signaling in rat cortical astrocytes. A rise in cytosolic Ca2+ ([Ca2+]cyt), resulting from mobilization of ER Ca2+ stores was followed by a rise in mitochondrial Ca2+ ([Ca2+]m, monitored using rhod-2). Whereas [Ca2+]cyt recovered within approximately 1 min, the ...

Cardiac hypothermia alters contractility and intracellular Ca2+ concentration ([Ca2+]i) homeostasis. We examined how left ventricular pressure (LVP) is altered as a function of cytosolic [Ca2+]iover a range of extracellular CaCl2 concentration ([CaCl2]e) during perfusion of isolated, paced guinea pig hearts at 37°C, 27°C, and 17°C. Transmural LV phasic [Ca2+] was measured using the Ca2+ indicat...

The relative importance of the Na+/Ca2+exchanger in the initial and terminal phases of relaxation and the decline in the [Ca2+]itransient was investigated in adult rabbit ventricular myocytes loaded with the Ca2+ indicator fluo 3. For electrically stimulated contractions, the peak intracellular Ca2+ concentration ([Ca2+]i) was 700 ± 87 nM and end-diastolic [Ca2+]iwas 239 ± 30 nM (0.25 Hz, 37°C,...

AbstractIn the present work we set out to investigate the neuroprotective effects of noscapine (0.5-2 µM) in presence of D-glucose on primary murine foetal cortical neurons after oxygen–glucose deprivation/24 hrs recovery. Cell viability, nitric oxide production and intracellular calcium ([ca2+]i) levels were evaluated by MTT assay, the modified Griess method and Fura-2 respectively. 25 and 100...

Altered sarcoplasmic reticulum (SR) Ca2+-ATPase and Na+-Ca2+ exchange (NCX) function have been implicated in depressing SR Ca2+ content and contractile function in heart failure (HF). Enhanced diastolic ryanodine receptor (RyR) leak could also lower SR Ca2+ load in HF, but direct cellular measurements are lacking. In this study, we measure SR Ca2+ leak directly in intact isolated rabbit ventric...

The process of Ca2+ release from sarcoplasmic reticulum (SR) comprises 4 phases in smooth muscle cells. Phase 1 is characterized by a large increase of the intracellular Ca2+ concentration ([Ca2+]i) with a minimal reduction of the free luminal SR [Ca2+] ([Ca2+]FSR). Importantly, active SR Ca2+ ATPases (SERCA pumps) are necessary for phase 1 to occur. This situation cannot be explained by the st...