thapsigargin and Acute-Disease

Sustained activation of the cytosolic calcium concentration induces injury to pancreatic acinar cells and necrosis. The calcium release-activated calcium modulator ORAI1 is the most abundant Ca(2+) entry channel in pancreatic acinar cells; it sustains calcium overload in mice exposed to toxins that induce pancreatitis. We investigated the roles of ORAI1 in pancreatic acinar cell injury and the development of acute pancreatitis in mice.. Mouse and human acinar cells, as well as HEK 293 cells transfected to express human ORAI1 with human stromal interaction molecule 1, were hyperstimulated or incubated with human bile acid, thapsigargin, or cyclopiazonic acid to induce calcium entry. GSK-7975A or CM_128 were added to some cells, which were analyzed by confocal and video microscopy and patch clamp recordings. Acute pancreatitis was induced in C57BL/6J mice by ductal injection of taurolithocholic acid 3-sulfate or intravenous' administration of cerulein or ethanol and palmitoleic acid. Some mice then were given GSK-7975A or CM_128, which inhibit ORAI1, at different time points to assess local and systemic effects.. GSK-7975A and CM_128 each separately inhibited toxin-induced activation of ORAI1 and/or activation of Ca(2+) currents after Ca(2+) release, in a concentration-dependent manner, in mouse and human pancreatic acinar cells (inhibition >90% of the levels observed in control cells). The ORAI1 inhibitors also prevented activation of the necrotic cell death pathway in mouse and human pancreatic acinar cells. GSK-7975A and CM_128 each inhibited all local and systemic features of acute pancreatitis in all 3 models, in dose- and time-dependent manners. The agents were significantly more effective, in a range of parameters, when given at 1 vs 6 hours after induction of pancreatitis.. Cytosolic calcium overload, mediated via ORAI1, contributes to the pathogenesis of acute pancreatitis. ORAI1 inhibitors might be developed for the treatment of patients with pancreatitis.

Topics: Acinar Cells; Acute Disease; Animals; Benzamides; Bile Acids and Salts; Calcium; Calcium Channels; Cells, Cultured; Disease Models, Animal; HEK293 Cells; Humans; Indoles; Mice; Mice, Inbred C57BL; ORAI1 Protein; Pancreatitis; Pyrazoles; Thapsigargin; Time Factors; Treatment Outcome

The role of intracellular calcium in acute thermal nociception was investigated in the mouse hot-plate test. Intracerebroventricular (i.c.v.) administration of TMB-8, a blocker of Ca++ release from intracellular stores, produced hypernociception. By contrast, i.c.v. pretreatment with thapsigargin, a depletor of Ca++ intracellular stores, produced an increase of the mouse pain threshold. Furthermore, non-analgesic doses of thapsigargin prevented the hypernociception produced by TMB-8. In mice undergoing treatment with heparin, an InsP3-receptor antagonist, or ryanodine, a ryanodine receptor (RyR) antagonist, a dose-dependent reduction of the pain threshold was observed. Pretreatment with D-myo inositol, compound which produces InsP3, and 4-chloro-m-cresol, a RyR agonist, induced an antinociceptive effect. The heparin hypernociception was prevented by D-myo inositol, but not by L-myo inositol, used as negative control. In the same experimental conditions, the antinociception induced by D-myo inositol was prevented by a non-hyperalgesic dose of heparin. Similarly, the reduction of pain threshold produced by ryanodine was reversed by non-analgesic doses of 4-chloro-m-cresol, whereas the antinocicpetion induced by 4-chloro-m-cresol was prevented by non-hyperalgesic doses of ryanodine. The pharmacological treatments employed did not produce any behavioral impairment of mice as revealed by the rota-rod and hole-board tests. These results indicate that a variation of intracellular calcium contents at a supraspinal level is involved in the modulation of acute thermal nociception. In particular, the stimulation of both InsP3- and Ry-receptors appears to play an important role in the induction of antinociception in mice, whereas a blockade of these receptors is involved in an hypernociceptive response to acute thermal pain.

Topics: Acute Disease; Animals; Behavior, Animal; Calcium; Calcium Channel Blockers; Calcium-Transporting ATPases; Dose-Response Relationship, Drug; Enzyme Inhibitors; Gallic Acid; Hot Temperature; Hyperalgesia; Injections, Intraventricular; Inositol 1,4,5-Trisphosphate; Male; Mice; Pain; Pain Threshold; Postural Balance; Reaction Time; Ryanodine Receptor Calcium Release Channel; Thapsigargin

To investigate whether the retina of the rat exerts a vasodilatory influence by the release of a relaxing factor and to characterize the retinal relaxing factor (RRF).. The relaxing influence of the rat retina was investigated by placing the retina in close proximity with a precontracted isolated rat carotid artery ring segment, mounted for isometric tension measurements.. Application of rat retina relaxed the artery in a reliable and reproducible way. The nitric oxide (NO)-synthase inhibitor N(omega)-nitro-L-arginine (L-NA), the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), and the removal of the endothelium of the artery all failed to affect the RRF response. The RRF response was not decreased; in contrast, it increased after treatment with a cyclooxygenase (COX) inhibitor (indomethacin or sodium diclofenac). Acute hypoxia largely enhanced retina-induced relaxation. Several potential mediators of hypoxia-induced vasodilation were excluded as candidates for the RRF or for mediating the enhanced response to RRF in hypoxia. Inhibition of the plasma membrane Ca(2+)-adenosine triphosphatase (ATPase) with vanadate significantly affected the RRF response.. The release of an as yet unidentified relaxing factor(s) from the rat retina was demonstrated. Acute hypoxia profoundly enhances the RRF response. None of the known mediators of hypoxia-induced vasodilation nor NO, prostanoids, or endothelial factors mediate the RRF response. Activation of the plasma membrane Ca(2+)-ATPase seems to be involved in the RRF response.

Topics: Acute Disease; Animals; Calcium-Transporting ATPases; Carotid Arteries; Cyclooxygenase Inhibitors; Diclofenac; Endothelium, Vascular; Enzyme Inhibitors; Female; Guanylate Cyclase; Hypoxia; In Vitro Techniques; Indomethacin; Isometric Contraction; Nitroarginine; Oxadiazoles; Quinoxalines; Rats; Rats, Wistar; Retina; Sarcoplasmic Reticulum; Thapsigargin; Vasodilation; Vasodilator Agents

We hypothesized that intracellular calcium overload may play an important role in heat-induced myocardial injury. This postulate was investigated using a model of isolated guinea pig papillary muscle in which resting tension was measured as an indirect indicator of cytosolic free-calcium concentration and the fluorescence changes of Fluo-3 AM dye was measured as a direct indicator of cytosolic free-calcium concentration.. Excised guinea pig right ventricular papillary muscles were attached to a force transducer in a high-flow tissue bath and superfused with Tyrode's solution at 37 degrees +/- 0.5 degrees C. The temperature was rapidly changed to between 38.0 degrees and 56.0 degrees C for 60 seconds and then returned to 37.0 degrees C. Hyperthermia caused a reversible increase in resting tension at temperatures between 45 degrees and 50 degrees C and irreversible contracture at > or =50 degrees C. Rapid cooling contracture experiments and experiments measuring fluorescence of myocytes loaded with 5 microM Fluo-3 AM dye demonstrated that the hyperthermia-induced rise in resting tension was likely due to an increase in intracellular calcium content. Inhibition of the sarcoplasmic reticulum calcium pump with 20 microM thapsigargin resulted in irreversible contracture of the papillary muscles at temperatures between 45 degrees and 50 degrees C and significant increases in Fluo-3 fluorescence at 48 degrees C. Blockade of sarcolemmal calcium channels with 0.5 mM cadmium or 40 microM verapamil did not attenuate the heat-induced increase in resting tension and Fluo-3 fluorescence.. Hyperthermia causes an increase in resting tension of cardiac muscle that most likely is mediated by a calcium channel-independent increase in calcium permeability of the sarcolemmal membrane and/or release of stored intracellular calcium.

Topics: Acute Disease; Animals; Calcium; Calcium Channel Blockers; Enzyme Inhibitors; Female; Guinea Pigs; Hyperthermia, Induced; Male; Models, Cardiovascular; Myocardial Contraction; Myocardial Reperfusion Injury; Papillary Muscles; Thapsigargin

Disruption of pancreatic exocrine secretion is an important feature of acute pancreatitis. Because cytosolic calcium is a key intracellular messenger controlling pancreatic secretion, this study examined patterns of calcium signaling during the early stages of cerulein-induced pancreatitis.. Mice were administered hourly intraperitoneal injections of cerulein (50 micrograms/kg), and paired controls were administered saline. Acini were isolated by collagenase from pancreatic tissue harvested after injections 1, 3, 5, and 7 and were loaded with Fura-2. Individual cellular calcium responses to acetylcholine and cholecystokinin were studied using digital imaging.. The proportion of cells maintaining a normal oscillatory calcium response to physiological secretagogue stimulation diminished progressively after increasing cerulein injections. Also, the normal polarized spatial pattern of calcium Increase within individual acinar cells was progressively lost. A sustained response to high-dose stimulation was maintained but with diminishing amplitude. The characteristic calcium response to the Ca(2+)-adenosine triphosphatase inhibitor thapsigargin was maintained, implying that calcium reuptake and extrusion were not impaired.. Progressive disruption of physiological patterns of pancreatic acinar cell calcium signaling, notably in the secretory pole of the cell, is an early feature of pancreatitis induced by cerulein hyperstimulation. These changes may be important in contributing to the disruption of exocrine secretion in acute pancreatitis.

Topics: Acetylcholine; Acute Disease; Animals; Calcium; Calcium-Transporting ATPases; Ceruletide; Cholecystokinin; Endoplasmic Reticulum; Enzyme Inhibitors; Male; Mice; Mice, Inbred Strains; Pancreas; Pancreatitis; Signal Transduction; Terpenes; Thapsigargin

The effects of hypoxia on the cytosolic Ca2+ concentration, [Ca2+]i, were characterized in cultured pulmonary arterial smooth muscle (PASM) cells. Reducing O2 tension (PO2) from 150 to < 25 Torr induced a reversible 100-200% increase in [Ca2+]i that was characterized by two components: an early rise in [Ca2+]i that was dependent on the rate, as well as the magnitude, of decline in PO2 and a later, steady-state increase that was independent of the rate at which PO2 changed. Caffeine lowered [Ca2+]i during normoxia and blocked the early component of the response to hypoxia, whereas the steady-state hypoxic response was only partially inhibited. Like hypoxia, thapsigargin (TG) elevated [Ca2+]i, and there was no additional hypoxia-induced elevation in [Ca2+]i at any time after exposure to TG. At steady state, the hypoxic responses were completely reversed by removal of extracellular Ca2+, whereas, on average, verapamil and nifedipine attenuated the hypoxia-induced increases in [Ca2+]i by only 44 and 35%, respectively. These results suggest that hypoxia-induced elevation of [Ca2+]i in PASM cells consists of an early release of Ca2+ from the sarcoplasmic reticulum and a later influx of extracellular Ca2+, in part, through nifedipine- and verapamil-insensitive Ca2+ channels. The results are consistent with the idea that hypoxia and thapsigargin may share common mechanisms for tonically increasing [Ca2+]i.

Topics: Acute Disease; Animals; Caffeine; Calcium; Calcium Channels; Calcium-Transporting ATPases; Cells, Cultured; Cytosol; Fura-2; Hypoxia; Male; Microscopy, Fluorescence; Muscle, Smooth, Vascular; Nifedipine; Oxygen; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Sarcoplasmic Reticulum; Terpenes; Thapsigargin; Verapamil