We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca(2+) efflux pathways (SERCA, Na(+)/Ca(2+) exchange, and sarcolemmal Ca(2+) ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca(2+) buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca(2+) in the dyad and bulk cytoplasm, on cellular Ca(2+) cycling. Increasing the dyadic fraction of a particular Ca(2+) efflux pathway increases the amount of Ca(2+) removed by that pathway, with corresponding changes in Ca(2+) efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca(2+) removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca(2+)-dependent inactivation of the L-type Ca(2+) current, resulted from the buffers acting as slow and fast "shuttles," respectively, removing Ca(2+) from the dyadic space. The data suggest that complex changes in dyadic Ca(2+) and cellular Ca(2+) cycling occur as a result of changes in the location of Ca(2+) removal pathways or the presence of exogenous Ca(2+) buffers, although changing the distribution of Ca(2+) efflux pathways has relatively small effects on the systolic Ca(2+) transient.
- MeSH
- biologické modely MeSH
- časové faktory MeSH
- EGTA analogy a deriváty farmakologie MeSH
- gating iontového kanálu účinky léků MeSH
- intracelulární prostor účinky léků metabolismus MeSH
- kardiomyocyty účinky léků metabolismus MeSH
- kompartmentace buňky MeSH
- krysa rodu rattus MeSH
- počítačová simulace MeSH
- pufry MeSH
- pumpa pro výměnu sodíku a vápníku metabolismus MeSH
- sarkolema účinky léků metabolismus MeSH
- srdeční komory cytologie MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Here we report for the first time the possibility of sequential sperm motility activation in sturgeon (sterlet, Acipenser ruthenus), a fish with external fertilization, through changes either in osmolality (global solute concentration) or in the Ca(2+) concentration of the medium surrounding the spermatozoa. Sperm motility was initiated in any of three solutions containing buffer and sucrose at 80, or 40 or 10mM (called S80, S40, S10, respectively); S80 is hypertonic relative to sterlet seminal fluid, while S40 is isotonic and S10 is hypotonic. After cessation of sperm movement at the end of this first motility period, a second and then a third, subsequent motile phase were observed. The second motility period was induced at cessation of motility in S80 by imposing a two-fold decrease in osmolality. After arrest of motility in this half-diluted S80, a third motility period could be initiated by addition of CaCl2 to 1mM final concentration. At the end of a first motility period in either S40 or S10, subsequent motility re-activation episodes were achieved only by addition of 1mM CaCl2. Depending on conditions in which sperm samples were activated, significant differences in curvilinear velocity, percent motile spermatozoa, motility duration time, and specific external features of spermatozoa flagella were observed. Altogether, these observations on the ability of sturgeon spermatozoa to sustain sequential activation episodes by experimental adjustment of their environmental conditions represent a potent model for deeper investigations on the sperm motility activation mechanisms.
- MeSH
- EGTA farmakologie MeSH
- kapacitace spermií účinky léků fyziologie MeSH
- motilita spermií účinky léků fyziologie MeSH
- osmolární koncentrace MeSH
- ryby fyziologie MeSH
- sperma chemie metabolismus MeSH
- spermie účinky léků fyziologie MeSH
- vápník farmakologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The present study shows the roles of osmolality, calcium (Ca(2+))-potassium (K(+)) antagonist and Ca(2+) in sperm activation and flagellar beating of a sturgeon species, sterlet (Acipenser ruthenus). Sperm motility was activated at hypoosmolality relative to seminal plasma and suppressed at 175 mOsmol kg(-1). Sperm activation was totally suppressed by 0.35mM K(+), but Ca(2+) could fully reverse K(+) inhibitory effect at Ca(2+): K(+) ratio of 0.25. Neither EGTA (a chelator of Ca(2+) ions) nor nifedipine (a Ca(2+) channel blocker) prevented sperm activation. But, sperm motility and velocity were significantly decreased by EGTA, nifedipine and an inhibitor for Ca(2+)/calmodulin activated phosphodiesterase (w-7) that suggest role of Ca(2+) signaling after triggering sperm activation through hypoosmolality. Symmetric flagellar beating was also turned to asymmetric after activation in w-7, which is an evidence for modulation of Ca(2+)-binding proteins activity. Sturgeon sperm, similar to salmonids, is immotile in seminal plasma due to high K(+) concentrations, but the mechanism of sperm activation seems to be closer to other fish species where osmolality prohibits sperm activation in seminal plasma. In these species, hypoosmolality is the primary signal for sperm Ca(2+)-dependent signaling of axonemal beating.
- MeSH
- bičík spermie účinky léků metabolismus fyziologie MeSH
- blokátory kalciových kanálů farmakologie MeSH
- chelátory farmakologie MeSH
- draslík farmakologie fyziologie MeSH
- EGTA farmakologie MeSH
- motilita spermií účinky léků MeSH
- nifedipin farmakologie MeSH
- osmolární koncentrace MeSH
- proteinkinasy závislé na vápníku a kalmodulinu antagonisté a inhibitory MeSH
- rybí proteiny antagonisté a inhibitory MeSH
- ryby MeSH
- sulfonamidy farmakologie MeSH
- vápník farmakologie fyziologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Trilobolide (TB), a sesquiterpene lactone isolated from Laser trilobum is an inhibitor of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA). We have found that upon the in vitro exposure to TB, rodent peritoneal cells and human peripheral blood mononuclear cells secrete high amounts of IFN-γ. The effect is associated with the stimulation of high output NO biosynthesis in rat cells. The stimulatory potential of TB depends on the activation of MAP kinases p38 and ERK1/2, and transcription factor NF-κB. BAPTA-AM, a chelator of the intracellular calcium, remained without any effect on the secretion of IFN-γ triggered by TB. These results demonstrate that TB is a potent immunostimulatory agent.
- MeSH
- butyráty farmakologie chemie MeSH
- EGTA analogy a deriváty farmakologie MeSH
- furany chemie farmakologie MeSH
- interferon gama metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- molekulární struktura MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- neutrofily účinky léků metabolismus MeSH
- oxid dusnatý metabolismus MeSH
- peritoneum cytologie MeSH
- potkani inbrední LEW MeSH
- viabilita buněk MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We studied hsBAFF activity in in vitro mouse splenic B cells. hsBAFF effects on intracellular free Ca2+ concentration ([Ca2+]i) were assayed, using a laser scanning confocal microscope with fluorescent probe, Fluo-3/AM. We showed that treatment of B cells with 0.5-5 µg/ml hsBAFF resulted in significantly higher [Ca2+]i levels in a dose-dependent fashion at 12 and 24 h, respectively (p<0.05 or p<0.01 vs. control). Furthermore, we noticed that 2.5 µg/ml hsBAFF-treated cells were significantly resistant to decrease of cellular viability induced by thapsigargin (Tg), an endoplasmic reticulum (ER) Ca2+-ATPase inhibitor (p<0.05 hsBAFF plus Tg group vs. Tg group). Thus hsBAFF may promote B cell survival by direct upregulation of [Ca2+]i physiological homeostasis contributing to prevention of [Ca2+]i dysfunction. Using immunocytochemistry and Western blot analysis, we found that the activation of ERK1/2 due to hsBAFF was triggered by a [Ca2+]i-dependent pathway, leading to elevation of B cell proliferation. This is supported by the findings that intracellular Ca2+ chelator BAPTA/AM attenuated phosphorylated ERK1/2 expression and cell proliferation in hsBAFF-stimulated B cells. hsBAFF-stimulated B cell proliferation was obviously reduced by mitogen extracellular kinase 1/2 (MEK1/2, upstream of ERK1/2) inhibitor U0126. Taken together, the main finding of this study is that hsBAFF elicits higher but homeostatic [Ca2+]i levels, which regulates ERK1/2 activity and cell proliferation in in vitro B cells
- MeSH
- B-lymfocyty enzymologie MeSH
- butadieny farmakologie MeSH
- časové faktory MeSH
- chelátory farmakologie MeSH
- EGTA analogy a deriváty farmakologie MeSH
- faktor aktivující B-buňky metabolismus MeSH
- financování organizované MeSH
- fosforylace MeSH
- homeostáza MeSH
- inhibitory enzymů farmakologie MeSH
- inhibitory proteinkinas farmakologie MeSH
- kultivované buňky MeSH
- lidé MeSH
- mitogenem aktivovaná proteinkinasa 1 metabolismus MeSH
- mitogenem aktivovaná proteinkinasa 3 metabolismus MeSH
- myši inbrední ICR MeSH
- myši MeSH
- nitrily farmakologie MeSH
- proliferace buněk MeSH
- sarkoplazmatická Ca2+-ATPáza antagonisté a inhibitory metabolismus MeSH
- thapsigargin farmakologie MeSH
- vápník metabolismus MeSH
- viabilita buněk MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
Hypotonic solution alters ion channel activity, but little attention has been paid to voltage-dependent sodium channels. The aim of this study was to investigate the effects of hypotonic solution on transient sodium currents (INaT) and persistent sodium currents (INaP). We also explored whether the intracellular signal transduction systems participated in the hypotonic modifications of sodium currents. INaT and INaP were recorded by means of whole-cell patch-clamp technique in isolated rat ventricular myocytes. Our results revealed that hypotonic solution reduced INaT and simultaneously augmented INaP with the occurrence of interconversion between INaT and INaP. Hypotonic solution shifted steady-state inactivation to a more negative potential, prolonged the time of recovery from inactivation, and enhanced intermediate inactivation (IIM). Ruthenium red (RR, inhibitor of TRPV4), bisindolylmaleimide VI (BIM, inhibitor of PKC), Kn-93 (inhibitor of Ca/CaMKII) and BAPTA (Ca2+-chelator) inhibited the effects of hypotonic solution on INaT and INaP. Therefore we conclude that hypotonic solution inhibits INaT, enhances INaP and IIM with the effects being reversible. TRPV4 and intracellular Ca2+, PKC and Ca/CaMKII participate in the hypotonic modifications of sodium currents.
- MeSH
- benzylaminy farmakologie MeSH
- chelátory farmakologie MeSH
- EGTA analogy a deriváty farmakologie MeSH
- financování organizované MeSH
- hypotonické roztoky MeSH
- indoly farmakologie MeSH
- inhibitory proteinkinas farmakologie MeSH
- kardiomyocyty metabolismus účinky léků MeSH
- kationtové kanály TRPV antagonisté a inhibitory metabolismus MeSH
- kinetika MeSH
- krysa rodu rattus MeSH
- maleimidy farmakologie MeSH
- membránové potenciály MeSH
- metoda terčíkového zámku MeSH
- proteinkinasa C antagonisté a inhibitory metabolismus MeSH
- proteinkinasa závislá na vápníku a kalmodulinu typ 2 antagonisté a inhibitory metabolismus MeSH
- rutheniová červeň farmakologie MeSH
- signální transdukce účinky léků MeSH
- sodík metabolismus MeSH
- srdeční komory cytologie metabolismus účinky léků MeSH
- sulfonamidy farmakologie MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
