Extracellular Ca2+ directly regulates tight junctional permeability in the human cervical cell line CaSki

1997 ◽  
Vol 272 (2) ◽  
pp. C511-C524 ◽  
Author(s):  
G. I. Gorodeski ◽  
W. Jin ◽  
U. Hopfer
Keyword(s):  
Tight Junctions ◽  
Calcium Concentration ◽  
Calcium Influx ◽  
Partial Agonist ◽  
Electrical Conductance ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Maximal Effect ◽  
Response Curves ◽  
Junctional Permeability

Lowering extracellular calcium concentration ([Ca2+]o) increases acutely and reversibly the transepithelial electrical conductance (G(TE)) and the epithelial permeability to pyranine (Ppyr) across CaSki cultures. Effects were already observed after lowering calcium from 1.2 to 1.0 mM and were maximal at 0.1 mM. The dose-response curves were sigmoidal (calcium concentration that produces half-maximal effect = 0.3 mM), and the time courses indicated simple exponential trends (time constants of 4-5 min). The effect of calcium was not mediated by mobilization of cytosolic calcium or altering calcium influx, and manganese was found to be a partial agonist to [Ca2+]o. The effects of [Ca2+]o, on permeability were additive to those of hypertonic conditions, indicating that calcium modulates junctional permeability. The experimental data were fitted to theoretical models that relate changes in G(TE) to the probability of assembled/disassembled tight junctions. The results suggest that calcium interacts directly and cooperatively at extracellular sites with junctional elements that are arranged in parallel, and it shifts the probability state of the junctions from "open" to "closed" state. Changes in extracellular calcium may affect the permeability of tight junctions of the cervical epithelium and may play a role in regulating production of cervical mucus.

Sevoflurane but not propofol provided dual effects of cell survival in human neuroblastoma SH-SY5Y cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Xue Gao ◽  
Xiu Wang ◽  
Lei Zhang ◽  
Ge Liang ◽  
Rachel Mund ◽  
...  
Keyword(s):  
Cell Survival ◽  
Prolonged Exposure ◽  
Calcium Influx ◽  
Cell Damage ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Mitochondrial Calcium ◽  
General Anesthetics ◽  
Wild Type ◽  
Human Neuroblastoma

Background: We have hypothesized that the most commonly used intravenous (propofol) and inhalational (sevoflurane) general anesthetics affect cell survival concentration and duration dependently with different potency associated with their differential potency to affect intracellular calcium homeostasis. Methods: Human neuroblastoma SH-SY5Y cells stably transfected with either wild type or M146L mutant human presenilin 1 were cultured and exposed to equipotent of propofol or sevoflurane. Cell viability, cytosolic and mitochondrial calcium were measured. Results: Sevoflurane but not propofol, at clinically relevant concentrations and durations, promoted cell survival. Prolonged exposure (24 hours) of 1% sevoflurane resulted in significant cell damage in both types of cells. Both sevoflurane and propofol had significantly higher cell response rates to the elevation of cytosolic calcium or mitochondrial calcium in the presence of extracellular calcium. With the contribution of calcium influx, sevoflurane but not equipotent 1 MAC propofol, caused a significantly greater increase in peak and overall calcium in Alzheimer’s mutation cell than in wild type cells, but significantly more increase in overall mitochondrial calcium concentrations in wild type than mutation cells. In the absence of extracellular calcium influx, sevoflurane, but not propofol, caused more significant elevations of overall mitochondrial calcium concentration in mutation cells than control cells. Conclusion: Calcium influx contributed to the general anesthetics mediated elevation of cytosolic or mitochondrial calcium, which is especially true for propofol. Sevoflurane has a greater potency to either promote or inhibit cell survival than propofol, which may be associated with its ability to affect cytosolic or mitochondrial calcium.

Requirement for transmembrane sodium flux in maintenance of cytosolic calcium levels in rat Sertoli cells

1993 ◽  
Vol 264 (6) ◽  
pp. E863-E867 ◽  
Author(s):  
E. Gorczynska ◽  
D. J. Handelsman
Keyword(s):  
Sertoli Cells ◽  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Ruthenium Red ◽  
Extracellular Calcium ◽  
Isolated Cells ◽  
Acetoxymethyl Ester ◽  
Calcium Fluxes ◽  
Calcium Exchange ◽  
Extracellular Sodium

The prompt rise in cytosolic calcium induced by follicle-stimulating hormone (FSH) in rat Sertoli cells suggests a role for calcium in FSH signal transduction. To evaluate the requirement for sodium in transmembrane calcium fluxes in Sertoli cells, we measured intracellular calcium concentration under sodium-free conditions and during stimulation by monensin and veratridine, used to elevate cytosolic sodium. Cytosolic calcium levels were measured by dual-wavelength spectrofluorimetry using freshly isolated cells loaded with fura-2 acetoxymethyl ester. Whereas, removal of extracellular sodium lowered cytosolic calcium in unstimulated cells from 89 +/- 4 to 75 +/- 8 nM, treatment with monensin and veratridine increased cytosolic calcium to 142 +/- 19 and 126 +/- 13 nM, respectively. Without extracellular calcium, monensin still produced 47% of the rise in cytosolic calcium observed in the presence of extracellular calcium, indicating approximately equal contributions of calcium from intracellular and extracellular sources. Blockade of voltage-sensitive or/and voltage-insensitive calcium channels by verapamil and ruthenium red was unable to completely prevent the monensin-induced elevation of cytosolic calcium. In addition tetrodotoxin failed to block the FSH-induced rise in cytosolic calcium. These observations, together with the considerable reduction in monensin-induced rise in cytosolic calcium under extracellular sodium-free condition, support the hypothesis that sodium-calcium exchange rather than the specific calcium or sodium channels regulate basal and monensin-induced transmembrane sodium and calcium fluxes in Sertoli cells.

Haloperidol-mediated phosphoinositide hydrolysis via direct activation of α1-adrenoceptors in frontal cerebral rat cortex

1999 ◽  
Vol 77 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Tania Gabriela Borda ◽  
Graciela Cremaschi ◽  
Leonor Sterin-Borda
Keyword(s):  
Inositol Phosphate ◽  
Partial Agonist ◽  
Phosphoinositide Hydrolysis ◽  
Maximal Effect ◽  
Response Curves ◽  
Pi Turnover ◽  
Direct Activation ◽  
Adrenoceptor Blocker ◽  
6 Hydroxydopamine ◽  
Pi Hydrolysis

In addition to its effect on D2 dopamine receptor blockades, haloperidol is able to interact with multiple neurotransmitters (NTs). Its action on phosphoinositide (PI) turnover was studied on cerebral cortex preparations. It induces an increase in inositol phosphate (IP) accumulation, which was only blunted by the α1-adrenoceptor blocker prazosin. Haloperidol maximal effect (Emax) was less than the effect of the full agonist norepinephrine (NE), and dose-response curves for both NE in the presence of submaximal doses of haloperidol and haloperidol in the presence of Emax doses of NE showed that haloperidol behaves as a partial agonist of cerebral α1-adrenoceptors. Its effect on PI hydrolysis is mediated through phospholipase C activation, as 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (NCDC) and 1-[6-([(17β)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino)hexyl]-1H-pyrrole-2,5-dione) (U-73122) were able to abrogate both haloperidol and NE actions. Further, the typical neuroleptic exerts a direct activation of α1-adrenoceptors as its actions were not modified by cocaine and persisted in spite of chemical rat cerebral denervation with 6-hydroxydopamine (6-OHDA). The possibility that this agonistic action on α1-adrenoceptors would be involved in haloperidol side effects is also discussed.Key words: haloperidol, neuroleptics, α1-adrenoceptor, phosphoinositide hydrolysis, cerebral frontal cortex.

Effect of osmolality on cytosolic free calcium and aldosterone secretion

1992 ◽  
Vol 262 (1) ◽  
pp. E68-E75 ◽  
Author(s):  
W. Wang ◽  
N. Hayama ◽  
T. V. Robinson ◽  
R. E. Kramer ◽  
E. G. Schneider
Keyword(s):  
Calcium Influx ◽  
Potassium Concentration ◽  
Sodium Concentration ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Free Calcium ◽  
Aldosterone Secretion ◽  
Voltage Dependent ◽  
Glomerulosa Cells ◽  
Dose Dependent

Alterations in extracellular osmolality have powerful inverse effects on basal and potassium- and angiotensin-stimulated aldosterone secretion. With the use of bovine glomerulosa cells grown in primary culture, the effects of alterations in osmolality on cytosolic calcium concentration ([Ca2+]c), efflux and uptake of 45Ca2+, and aldosterone secretion were determined. Alterations in osmolality, independent of sodium concentration, have inverse effects on aldosterone secretion, which are correlated with simultaneous changes in [Ca2+]c measured using fura-2. Reductions in osmolality cause dose-dependent biphasic increases in [Ca2+]c different from the monophasic increases in [Ca2+]c produced by increases in potassium concentration. Like potassium- and angiotensin-stimulated increases in [Ca2+]c, hypotonically induced increases in [Ca2+]c are associated with an increase in 45Ca2+ efflux. Reductions in osmolality also increased the uptake of 45Ca2+, an effect apparent at 2 min and persistent for at least 30 min. In the absence of extracellular calcium, reductions in osmolality, as increases in potassium concentration but not angiotensin, fail to increase [Ca2+]c, efflux of 45Ca2+, or aldosterone secretion. In conclusion, osmolality-induced alterations in aldosterone secretion are associated with parallel changes in [Ca2+]c, effects caused by alteration in the influx of extracellular calcium. On the basis of these and previous studies, we hypothesize that osmolality affects calcium influx by activating voltage-dependent or stretch-activated calcium channels.

scholarly journals The role of calcium in the age-related decline of neutrophil function

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 659-665 ◽  
Author(s):  
DA Lipschitz ◽  
KB Udupa ◽  
LA Boxer
Keyword(s):  
Calcium Homeostasis ◽  
Calcium Concentration ◽  
Cytochalasin B ◽  
Cytosolic Calcium ◽  
Neutrophil Function ◽  
Extracellular Calcium ◽  
Cytosolic Calcium Concentration ◽  
Age Related ◽  
Improved Function

Abstract Upon activation by formyl-methionyl-leucyl-phenylalanine (FMLP), either in the presence of absence of cytochalasin B, neutrophils from old subjects generated significantly less superoxide than did neutrophils from the young. This reduction in activity was associated with a significant decrease in the basal cytosolic calcium concentration and a diminished flux of calcium to the cytosol after activation. At all concentrations of FMLP tested, cytosolic calcium remained significantly lower in neutrophils from the old as compared with the young, whereas permeability to extracellular calcium and efflux of calcium from the cell were also significantly diminished. Pretreatment of the cell with the ionophore ionomycin elevated the cytosolic calcium concentration and significantly improved function in old neutrophils. These findings demonstrate that aging results in alterations in neutrophil calcium homeostasis that may play a role in the age-related decline in neutrophil function.

α1-Adrenergic stimulation increases the Vmax of isolated myocardial papillary muscles

1991 ◽  
Vol 69 (12) ◽  
pp. 1804-1809 ◽  
Author(s):  
Kai Li ◽  
Jean L. Rouleau
Keyword(s):  
Calcium Concentration ◽  
Maximum Velocity ◽  
Cytosolic Calcium ◽  
Threshold Concentration ◽  
Extracellular Calcium ◽  
Papillary Muscles ◽  
Adrenergic Stimulation ◽  
Experimental Conditions ◽  
Extracellular Calcium Concentration ◽  
Rabbit Myocardium

α-Adrenergic agonists have been shown to increase the tension developed by myocardial muscle. However, their effects on the maximum velocity of unloaded muscle shortening (Vmax) have not been rigorously examined. In this study, the contractile effects of the α-adrenergic agonist phenylephrine were examined in the presence of propranolol in papillary muscles of two species, the dog and the rabbit. In rabbit papillary muscles studied at physiological calcium concentrations (1.25 mM), phenylephrine increased all indices of contractility (Vmax, tension, and maximum rate of tension developed (dT/dt)) starting at 10−8 M. The percent increase in Vmax (121 ± 8%) was less than that of tension (188 ± 20%, p < 0.05) and dT/dt (262 ± 35%, p < 0.01). These findings occurred at both 29 and 35 °C and were inhibited by adding 10−5 M prazosin. Increasing extracellular calcium concentration from 1.25 to 15 mM caused changes in twitch configuration that were significantly different from those of phenylephrine. Calcium increased all indices of contractility more than did phenylephrine. This was particularly true for dT/dt (502 ± 82 vs. 262 ± 35% for phenylephrine, p < 0.01). Nonetheless, the ratio of increase in tension to increase in Vmax under both experimental conditions was similar (the increase in Vmax was 64% of that of tension with phenylephrine and 69% with increased calcium). At 1.25 mM calcium, the increase in contractility caused by phenylephrine was much smaller in dog myocardium as compared with rabbit myocardium. Rather, the effects of phenylephrine on dog myocardium studied at 1.25 mM calcium resembled that of rabbit myocardium studied at 15 mM calcium. We conclude that (i) α1-adrenergic receptor stimulation increases all indices of contractility at a similar threshold concentration but increases Vmax relatively less; (ii) despite markedly different effects on the intensity of the cytosolic calcium transient and twitch configuration characteristics, the increase in Vmax relative to tension caused by phenylephrine is similar to that caused by increasing extracellular calcium concentration; (iii) species differences in myocardial contractile response to α1-adrenergic stimulation exist, and that some of these differences can be abolished by altering extracellular calcium.Key words: α1-adrenergic, Vmax, contractility, calcium.

scholarly journals The role of calcium in the age-related decline of neutrophil function

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 659-665 ◽  
Author(s):  
DA Lipschitz ◽  
KB Udupa ◽  
LA Boxer
Keyword(s):  
Calcium Homeostasis ◽  
Calcium Concentration ◽  
Cytochalasin B ◽  
Cytosolic Calcium ◽  
Neutrophil Function ◽  
Extracellular Calcium ◽  
Cytosolic Calcium Concentration ◽  
Age Related ◽  
Improved Function

Upon activation by formyl-methionyl-leucyl-phenylalanine (FMLP), either in the presence of absence of cytochalasin B, neutrophils from old subjects generated significantly less superoxide than did neutrophils from the young. This reduction in activity was associated with a significant decrease in the basal cytosolic calcium concentration and a diminished flux of calcium to the cytosol after activation. At all concentrations of FMLP tested, cytosolic calcium remained significantly lower in neutrophils from the old as compared with the young, whereas permeability to extracellular calcium and efflux of calcium from the cell were also significantly diminished. Pretreatment of the cell with the ionophore ionomycin elevated the cytosolic calcium concentration and significantly improved function in old neutrophils. These findings demonstrate that aging results in alterations in neutrophil calcium homeostasis that may play a role in the age-related decline in neutrophil function.

pH-dependent regulation of lysosomal calcium in macrophages

2002 ◽  
Vol 115 (3) ◽  
pp. 599-607 ◽  
Author(s):  
Kenneth A. Christensen ◽  
Jesse T. Myers ◽  
Joel A. Swanson
Keyword(s):  
Calcium Binding ◽  
Calcium Concentration ◽  
Ph Dependence ◽  
Extracellular Fluid ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Free Calcium ◽  
Time Resolved ◽  
Lysosomal Ph ◽  
Ph Dependent

Calcium measurements in acidic vacuolar compartments of living cells are few, primarily because calibration of fluorescent probes for calcium requires knowledge of pH and the pH-dependence of the probe calcium-binding affinities. Here we report pH-corrected measurements of free calcium concentrations in lysosomes of mouse macrophages, using both ratiometric and time-resolved fluorescence microscopy of probes for pH and calcium. Average free calcium concentration in macrophage lysosomes was 4-6×10-4 M, less than half of the extracellular calcium concentration, but much higher than cytosolic calcium levels. Incubating cells in varying extracellular calcium concentrations did not alter lysosomal pH, and had only a modest effect on lysosomal calcium concentrations, indicating that endocytosis of extracellular fluid provided a small but measurable contribution to lysosomal calcium concentrations. By contrast, increases in lysosomal pH, mediated by either bafilomycin A1 or ammonium chloride, decreased lysosomal calcium concentrations by several orders of magnitude. Re-acidification of the lysosomes allowed rapid recovery of lysosomal calcium concentrations to higher concentrations. pH-dependent reductions of lysosomal calcium concentrations appeared to result from calcium movement out of lysosomes into cytoplasm,since increases in cytosolic calcium levels could be detected upon lysosome alkalinization. These studies indicate that lysosomal calcium concentration is high and is maintained in part by the proton gradient across lysosomal membranes. Moreover, lysosomes could provide an intracellular source for physiological increases in cytosolic calcium levels.

Resting load regulates vascular sensitivity by a cytosolic Ca(2+)-insensitive mechanism

1995 ◽  
Vol 268 (6) ◽  
pp. C1332-C1341 ◽  
Author(s):  
Y. Miyagi ◽  
S. Kobayashi ◽  
J. Nishimura ◽  
M. Fukui ◽  
H. Kanaide
Keyword(s):  
Calcium Concentration ◽  
Smooth Muscles ◽  
Cytosolic Calcium ◽  
Vascular Smooth Muscles ◽  
Response Curves ◽  
Force Development ◽  
Optimal Load ◽  
High K ◽  
Vascular Sensitivity ◽  
The Right

The cellular mechanism underlying the regulation of the contraction of vascular smooth muscles by resting load is unknown. To determine the effects of changes in the resting load on vascular sensitivity to high K+ and to 9,11-dideoxy-11 alpha, 9 alpha-epoxy-methanoprostaglandin F2 alpha (U-46619), the force and cytosolic calcium concentration ([Ca2+]i) of arterial strips were recorded at resting loads of 200 (optimal load), 50, and 10 mg. A decrease in the resting load elicited a small decrease in the basal [Ca2+]i level without affecting the extent of maximal [Ca2+]i elevation induced by either stimulus. Through a decrease in the resting load, the concentration-response curves for the force development of high K+ or of U-46619 shifted to the right, whereas those for [Ca2+]i did not. We conclude that the basal [Ca2+]i level and the force development, but not the agonist-induced [Ca2+]i signals, of vascular smooth muscles depend on the resting load. We response that the resting load regulates the sensitivity of vascular smooth muscles, irrespective of types of stimuli, through a [Ca2+]i-insensitive mechanism.

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