Cytosolic calcium, oxygen consumption and the intracellular pH of stimulated neutrophils

1988 ◽  
Vol 8 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Patricia E. Nasmith ◽  
Sergio Grinstein
Keyword(s):  
Oxygen Consumption ◽  
Intracellular Ph ◽  
Cytosolic Calcium ◽  
Cytoplasmic Ph ◽  
Acid Generation ◽  
Cytoplasmic Acidification ◽  
Free Media ◽  
Stimulation Of

The cytoplasmic pH undergoes a biphasic change when neutrophils are activated. The role of Ca2+ in initiating these changes was investigated. No correlation was found between the increased cytosolic [Ca2+] and the stimulation of the Na+/H+ antiport. Similarly, the cytoplasmic acidification elicited by activation in Na+-free media was found to be unrelated to [Ca2+]. Reversal of Na+/H+ exchange was also ruled out as the source of the acidification. Data using a variety of soluble activators indicate that metabolic acid generation is largely responsible for the observed drop in cytoplasmic pH.

scholarly journals Cytoplasmic [Ca2+] and intracellular pH in lymphocytes. Role of membrane potential and volume-activated Na+/H+ exchange.

1987 ◽  
Vol 89 (2) ◽  
pp. 185-213 ◽  
Author(s):  
S Grinstein ◽  
S Cohen
Keyword(s):  
Protein Kinase C ◽  
Membrane Potential ◽  
Protein Kinase ◽  
Intracellular Ph ◽  
Enzyme Treatment ◽  
Membrane Hyperpolarization ◽  
Kinase C ◽  
Free Media ◽  
Stimulation Of

The effect of elevating cytoplasmic Ca2+ [( Ca2+]i) on the intracellular pH (pHi) of thymic lymphocytes was investigated. In Na+-containing media, treatment of the cells with ionomycin, a divalent cation ionophore, induced a moderate cytoplasmic alkalinization. In the presence of amiloride or in Na+-free media, an acidification was observed. This acidification is at least partly due to H+ (equivalent) uptake in response to membrane hyperpolarization since: it was enhanced by pretreatment with conductive protonophores, it could be mimicked by valinomycin, and it was decreased by depolarization with K+ or gramicidin. In addition, activation of metabolic H+ production also contributes to the acidification. The alkalinization is due to Na+/H+ exchange inasmuch as it is Na+ dependent, amiloride sensitive, and accompanied by H+ efflux and net Na+ gain. A shift in the pHi dependence underlies the activation of the antiport. The effect of [Ca2+]i on Na+/H+ exchange was not associated with redistribution of protein kinase C and was also observed in cells previously depleted of this enzyme. Treatment with ionomycin induced significant cell shrinking. Prevention of shrinking largely eliminated the activation of the antiport. Moreover, a comparable shrinking produced by hypertonic media also activated the antiport. It is concluded that stimulation of Na+/H+ exchange by elevation of [Ca2+]i is due, at least in part, to cell shrinking and does not require stimulation of protein kinase C.

scholarly journals Dominant regulation of interendothelial cell gap formation by calcium-inhibited type 6 adenylyl cyclase

2002 ◽  
Vol 157 (7) ◽  
pp. 1267-1278 ◽  
Author(s):  
Donna L. Cioffi ◽  
Timothy M. Moore ◽  
Jerry Schaack ◽  
Judy R. Creighton ◽  
Dermot M.F. Cooper ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
Physiological Role ◽  
Cell Types ◽  
Cytosolic Calcium ◽  
Calcium Entry ◽  
Gap Formation ◽  
Calcium Stimulation ◽  
Store Operated Calcium Entry ◽  
Stimulation Of

Acute transitions in cytosolic calcium ([Ca2+]i) through store-operated calcium entry channels catalyze interendothelial cell gap formation that increases permeability. However, the rise in [Ca2+]i only disrupts barrier function in the absence of a rise in cAMP. Discovery that type 6 adenylyl cyclase (AC6; EC 4.6.6.1) is inhibited by calcium entry through store-operated calcium entry pathways provided a plausible explanation for how inflammatory [Ca2+]i mediators may decrease cAMP necessary for endothelial cell gap formation. [Ca2+]i mediators only modestly decrease global cAMP concentrations and thus, to date, the physiological role of AC6 is unresolved. Present studies used an adenoviral construct that expresses the calcium-stimulated AC8 to convert normal calcium inhibition into stimulation of cAMP, within physiologically relevant concentration ranges. Thrombin stimulated a dose-dependent [Ca2+]i rise in both pulmonary artery (PAECs) and microvascular (PMVEC) endothelial cells, and promoted intercellular gap formation in both cell types. In PAECs, gap formation was progressive over 2 h, whereas in PMVECs, gap formation was rapid (within 10 min) and gaps resealed within 2 h. Expression of AC8 resulted in a modest calcium stimulation of cAMP, which virtually abolished thrombin-induced gap formation in PMVECs. Findings provide the first direct evidence that calcium inhibition of AC6 is essential for endothelial gap formation.

Role of intracellular pH as a signal in the stimulation of pancreatic islets

1988 ◽  
Vol 16 (5) ◽  
pp. 807-808
Author(s):  
LEONARD BEST ◽  
ELIZABETH A. BONE ◽  
JUDITH E. MEATS ◽  
STEPHEN TOMLINSON
Keyword(s):  
Pancreatic Islets ◽  
Intracellular Ph ◽  
Stimulation Of

Stimulation of H+ secretion by CO2 in turtle bladder: role of intracellular pH, exocytosis, and calcium

1990 ◽  
Vol 258 (1) ◽  
pp. R222-R231
Author(s):  
J. A. Arruda ◽  
G. Dytko ◽  
Z. Talor
Keyword(s):  
Intracellular Calcium ◽  
Intracellular Ph ◽  
Fluorescent Dye ◽  
Isolated Cells ◽  
Cell Calcium ◽  
Turtle Bladder ◽  
Early Increase ◽  
Stimulation Of ◽  
Related Increase

We studied the interaction of intracellular pH, exocytosis, and cell calcium on the stimulation of H+ secretion by CO2 in turtle bladder. Intracellular pH was continuously monitored by the fluorescent dye 6-carboxyfluorescein and exocytosis was monitored by the release of mucosal fluorescein dextran. The initial stimulation of H+ secretion by 1 or 5% CO2 added to the serosal solution was accompanied by a similar and temporally related increase in exocytosis. Furthermore, a decrease in intracellular pH seems necessary for the early increase in H+ secretion and exocytosis. Because calcium plays an important role in exocytosis, we measured intracellular calcium in isolated cells with the fluorescent dye quin2. An increase in intracellular calcium (from 50 to 100 nM) was observed in isolated turtle bladder epithelial cells gassed with 5% CO2. To further evaluate the role of intracellular calcium on H+ secretion and exocytosis we utilized agents that alter cell calcium such as trifluoperazine and lanthanum. In the presence of CO2 these agents blocked partially the increase in H+ secretion and exocytosis but did not affect the decrease in intracellular H+. In conclusion, exocytosis, intracellular pH, and intracellular calcium play a key role in mediating CO2-stimulated H+ secretion in the turtle bladder.

Potassium-Induced Stimulation of Glutamate Uptake in Mouse Cerebral Astrocytes: The Role of Intracellular pH

2002 ◽  
Vol 66 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Michael G. Judd ◽  
Tavarekere N. Nagaraja ◽  
Neville Brookes
Keyword(s):  
Intracellular Ph ◽  
Glutamate Uptake ◽  
Stimulation Of

Relation between free cytosolic calcium and amylase release by pancreatic acini

1985 ◽  
Vol 249 (3) ◽  
pp. G389-G398 ◽  
Author(s):  
D. L. Ochs ◽  
J. I. Korenbrot ◽  
J. A. Williams
Keyword(s):  
Acinar Cells ◽  
Cytosolic Calcium ◽  
Pancreatic Acinar Cells ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Intracellular Ca ◽  
Free Media ◽  
Induced Changes ◽  
Stoichiometric Relation ◽  
Stimulation Of

Pancreatic acini were loaded with the Ca-selective fluorescent indicator quin-2 by incubation with its acetyoxymethyl ester. Loading acini with 844 +/- 133 microM quin-2 altered neither their ultrastructure nor their viability. The rate of amylase release from quin-2-loaded acini in response to the secretagogue carbachol, however, was significantly smaller than that of control acini. Studies in which acini were loaded with both quin-2 and a similar Ca-chelating compound, BAPTA, indicated that this reduced amylase release was related to the Ca buffering properties of quin-2. The concentration of free intracellular Ca calculated from the fluorescence of quin-2 was 90 +/- 18 nM. Stimulation by carbachol of acini suspended in media containing 1.25 mM Ca caused a rapid, transient enhancement of this value. After stimulation amylase release, the onset of the rise in free cytosolic Ca levels was observed in 1.1 +/- 0.1 s following the addition of agonist, and peak Ca levels (545 +/- 112 nM) were obtained within 5.3 +/- 0.3 s. For concentrations of carbachol less than or equal to 10(-6) M, a stoichiometric relation was found between stimulated amylase release and the peak concentration of free cytosolic Ca achieved. At higher concentrations of carbachol, however, the peak free cytosolic Ca remained constant while amylase release declined. The latency of the rise in intracellular Ca following stimulation of acini suspended in Ca-free media was not different from that observed for acini suspended in normal media, but the rise time was significantly prolonged. In the presence of extracellular Ca, the intracellular level of Ca remained elevated 2.8-fold above basal levels for at least 15 min following stimulation with 10(-6) M carbachol, whereas it had returned to near resting levels by 15 min when either 3 X 10(-7) or 3 X 10(-5) M carbachol was the stimulus. The Ca ionophore ionomycin (10–6 M) induced changes in the level of free cytosolic Ca similar to those caused by 10(-6) M carbachol. Ionomycin, however, stimulated only approximately one-third as much amylase release. These data suggest that factors in addition to changes in free cytosolic Ca may be important in regulating enzyme secretion by pancreatic acinar cells.

THE ROLE OF LACTATE IN THE STIMULATION OF THE OXYGEN CONSUMPTION OF FROG MUSCLE BY INSULIN

1964 ◽  
Vol 42 (1) ◽  
pp. 139-151 ◽  
Author(s):  
D. R. H. Gourley ◽  
Kenneth C. Fisher
Keyword(s):  
Oxygen Consumption ◽  
Major Effect ◽  
Ringer Solution ◽  
Frog Muscle ◽  
Complete Oxidation ◽  
Rate Of Oxygen Consumption ◽  
Lactate Utilization ◽  
Stimulation Of ◽  
Extra Oxygen

Lactate, citrate, succinate, or acetate added to isolated muscles suspended in Ringer solution in a Warburg flask produced an increase in the rate of oxygen consumption by the muscles. At a given molar concentration of these substances the increase was greatest with lactate and was progressively less with the addenda in the order given. When the concentration of each substance was adjusted so that the rate of oxygen consumption was the same with all of them, the addition of insulin produced an increase in the oxygen uptake which was of the same magnitude in each case. Evidence is presented which suggests that by causing spontaneous activity in the muscle, the acetate, succinate, and citrate may bring about a production of lactate.The extra oxygen consumed upon the addition of lactate could account for the complete oxidation of only a small part of the lactate which actually disappeared in an experiment. By assuming that all of this extra oxygen was used in the complete oxidation of lactate, it was calculated from the total lactate utilization in the presence or absence of insulin that the major effect of insulin was on the fraction of utilized lactate which was oxidized. This conclusion was also suggested by experiments with monoiodoacetate.

gp91phox-containing NAD(P)H oxidase mediates attenuation of nitric oxide-dependent control of myocardial oxygen consumption by ANG II

2005 ◽  
Vol 289 (2) ◽  
pp. H862-H867 ◽  
Author(s):  
Shintaro Kinugawa ◽  
Juhua Zhang ◽  
Eric Messina ◽  
Erin Walsh ◽  
Harer Huang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Oxygen Consumption ◽  
Myocardial Oxygen Consumption ◽  
Inflammatory Cells ◽  
Oxygen Electrode ◽  
No Production ◽  
Ang Ii ◽  
Wild Type ◽  
Stimulation Of

We have previously reported that ANG II stimulation increased superoxide anion (O2−) through the activation of NAD(P)H oxidase and inhibited nitric oxide (NO)-dependent control of myocardial oxygen consumption (MV̇o2) by scavenging NO. Our objective was to investigate the role of NAD(P)H oxidase, especially the gp91phox subunit, in the NO-dependent control of MV̇o2. MV̇o2 in mice with defects in the expression of gp91phox [gp91phox(−/−)] was measured with a Clark-type oxygen electrode. Baseline MV̇o2 was not significantly different between wild-type (WT) and gp91phox(−/−) mice. Stimulation of NO production by bradykinin (BK) induced significant decreases in MV̇o2 in WT mice. BK-induced reduction in MV̇o2 was enhanced in gp91phox(−/−) mice. BK-induced reduction in MV̇o2 in WT mice was attenuated by 10−8 mol/l ANG II, which was restored by coincubation with Tiron or apocynin. In contrast to WT mice, BK-induced reduction in MV̇o2 in gp91phox(−/−) mice was not altered by ANG II. There was a decrease in lucigenin (5 × 10−6 mol/l)-detectable O2− in gp91phox(−/−) mice compared with WT mice. ANG II resulted in significant increases in O2− production in WT mice, which was inhibited by coincubation with Tiron or apocynin. However, ANG II had no effect on O2− production in gp91phox(−/−) mice. Histological examination showed that the development of abscesses and/or the invasion of inflammatory cells occurred in lungs and livers but not in hearts and kidneys from gp91phox(−/−) mice. These results indicate that the gp91phox subunit of NAD(P)H oxidase mediates O2− production through the activation of NAD(P)H oxidase and attenuation of NO-dependent control of MV̇o2 by ANG II.

Cytosolic free calcium regulation in response to acute changes in intracellular pH in vascular smooth muscle

1993 ◽  
Vol 264 (4) ◽  
pp. C932-C943 ◽  
Author(s):  
D. C. Batlle ◽  
R. Peces ◽  
M. S. LaPointe ◽  
M. Ye ◽  
J. T. Daugirdas
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Intracellular Ph ◽  
Cytosolic Calcium ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Intracellular Store ◽  
Acute Changes ◽  
Free Media ◽  
Intracellular Alkalinization

This study examined the mechanisms whereby alterations of intracellular pH (pHi) impact on free cytosolic calcium (Cai2+) in cultured rat aortic vascular smooth muscle cells (VSMC) assayed in the presence of HCO3/CO2. Rapid cell alkalinization, effected by the exposure to NH4Cl or removal of CO2 from the superfusate, produced a rapid increase in Cai2+. The rise in Cai2+ was markedly diminished when sarcoplasmic reticulum (SR) Ca2+ stores had been depleted by prior exposure to arginine vasopressin (AVP) in Ca(2+)-free media or when SR release and reuptake of Ca2+ were blocked by the addition of 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester (TMB-8), but was unaffected by the removal of external Ca2+ or inhibition of Ca2+ entry using NiCl2. Cell acidification also resulted in a rapid increase in Cai2+. This Cai2+ increase was most apparent when pHi was very low (< 6.6) and was unaffected by removal of external Ca2+ or NiCl2 addition. Unlike the effect of cell alkalinization, the increase in Cai2+ associated with cell acidification was not prevented by pretreatment with AVP or TMB-8. We conclude that, in cultured VSMC, acute intracellular alkalinization and, to a lesser extent, acidification result in release of Ca2+ from internal stores. Alkalinization increases Cai2+ by promoting its release from a store which is AVP and TMB-8 sensitive, most likely the SR. Cell acidification increases Cai2+ from an intracellular store(s) that is neither AVP nor TMB-8 sensitive. The increase in Cai2+ produced by cell acidification may be explained on the basis of cell buffering such that, as cytosolic H+ increases, it displaces Cai2+ from internal buffers with similar affinities for Ca2+ and H+.

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