Abstract
The role of Na+ and Na+ exchangers in intracellular Ca2+ elevation and leukotriene B4 (LTBs) formation was investigated in granulocyte macrophage colony-stimulating factor (GM-CSF)-primed, fMLP-stimulated human neutrophils. Isotonic substitution of extracellular Na+ with N-methyl-D-glucamine+ (NMDG +) resulted in over 85% inhibition of the LTBs generation observed (from 14.1±0.9pmol/106 neutrophils to 1.7±1.0pmol/ 106 neutrophils at 0.3μM fMLP). Isotonic substitution of Na + with NMDG+ also induced a significant inhibition of fMLP-induced rise in cytosolic Ca2+ concentration ([Ca 2+]i) (from 2.17- to 0.78-fold increase over basal levels). Pretreatment with an inhibitor of the Na+/Ca2+ exchanger (benzamil) did not inhibit either [Ca2+]i rise or LTBs production, indicating that the observed effects of extracellular Na+-deprivation were unrelated to the Na+/Ca2+ exchanger in receptor-mediated Ca2+ influx, as previously hypothesized. LTBs production by thapsigargin-activated neutrophils was not affected by Na+ depletion, but was totally abolished in the presence of EGTA, suggesting that store depletion-driven extracellular Ca2+ influx is required for leukotriene synthesis and that this process is independent of Na+-deprivation. Exposure to Na+-free medium for the time of GM-CSF priming led to a significant decrease of intracellular pH values, suggesting a role of the Na+/H+ exchanger in intracellular Na+ depletion. Reducing the time of Na+-deprivation totally reversed the observed effect on LTBs production, resulting in enhanced, rather than inhibited, formation of LTBs. These results indicate that LTBs generation and [Ca2+]i rise in human neutrophils primed by GM-CSF and stimulated with fMLP is dependent on intracellular Na+ concentration, and, at variance with previously published results, unrelated to the Ca2+ influx through the Na+/Ca2+ exchanger.
| Original language | English |
|---|---|
| Pages (from-to) | 385-393 |
| Number of pages | 9 |
| Journal | Biochemical Pharmacology |
| Volume | 67 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jan 15 2004 |
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Keywords
- Calcium ion
- Leukotriene B
- Neutrophils
- Sodium ion
ASJC Scopus subject areas
- Pharmacology
Cite this
Role of sodium in intracellular calcium elevation and leukotriene B 4 formation by receptor-mediated activation of human neutrophils. / Tedeschi, Alberto; Ciceri, Paola; Zarini, Simona; Lorini, Maurizio; Di Donato, Manuela; Nicosia, Simonetta; Miadonna, Antonio; Sala, Angelo.
In: Biochemical Pharmacology, Vol. 67, No. 2, 15.01.2004, p. 385-393.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Role of sodium in intracellular calcium elevation and leukotriene B 4 formation by receptor-mediated activation of human neutrophils
AU - Tedeschi, Alberto
AU - Ciceri, Paola
AU - Zarini, Simona
AU - Lorini, Maurizio
AU - Di Donato, Manuela
AU - Nicosia, Simonetta
AU - Miadonna, Antonio
AU - Sala, Angelo
PY - 2004/1/15
Y1 - 2004/1/15
N2 - The role of Na+ and Na+ exchangers in intracellular Ca2+ elevation and leukotriene B4 (LTBs) formation was investigated in granulocyte macrophage colony-stimulating factor (GM-CSF)-primed, fMLP-stimulated human neutrophils. Isotonic substitution of extracellular Na+ with N-methyl-D-glucamine+ (NMDG +) resulted in over 85% inhibition of the LTBs generation observed (from 14.1±0.9pmol/106 neutrophils to 1.7±1.0pmol/ 106 neutrophils at 0.3μM fMLP). Isotonic substitution of Na + with NMDG+ also induced a significant inhibition of fMLP-induced rise in cytosolic Ca2+ concentration ([Ca 2+]i) (from 2.17- to 0.78-fold increase over basal levels). Pretreatment with an inhibitor of the Na+/Ca2+ exchanger (benzamil) did not inhibit either [Ca2+]i rise or LTBs production, indicating that the observed effects of extracellular Na+-deprivation were unrelated to the Na+/Ca2+ exchanger in receptor-mediated Ca2+ influx, as previously hypothesized. LTBs production by thapsigargin-activated neutrophils was not affected by Na+ depletion, but was totally abolished in the presence of EGTA, suggesting that store depletion-driven extracellular Ca2+ influx is required for leukotriene synthesis and that this process is independent of Na+-deprivation. Exposure to Na+-free medium for the time of GM-CSF priming led to a significant decrease of intracellular pH values, suggesting a role of the Na+/H+ exchanger in intracellular Na+ depletion. Reducing the time of Na+-deprivation totally reversed the observed effect on LTBs production, resulting in enhanced, rather than inhibited, formation of LTBs. These results indicate that LTBs generation and [Ca2+]i rise in human neutrophils primed by GM-CSF and stimulated with fMLP is dependent on intracellular Na+ concentration, and, at variance with previously published results, unrelated to the Ca2+ influx through the Na+/Ca2+ exchanger.
AB - The role of Na+ and Na+ exchangers in intracellular Ca2+ elevation and leukotriene B4 (LTBs) formation was investigated in granulocyte macrophage colony-stimulating factor (GM-CSF)-primed, fMLP-stimulated human neutrophils. Isotonic substitution of extracellular Na+ with N-methyl-D-glucamine+ (NMDG +) resulted in over 85% inhibition of the LTBs generation observed (from 14.1±0.9pmol/106 neutrophils to 1.7±1.0pmol/ 106 neutrophils at 0.3μM fMLP). Isotonic substitution of Na + with NMDG+ also induced a significant inhibition of fMLP-induced rise in cytosolic Ca2+ concentration ([Ca 2+]i) (from 2.17- to 0.78-fold increase over basal levels). Pretreatment with an inhibitor of the Na+/Ca2+ exchanger (benzamil) did not inhibit either [Ca2+]i rise or LTBs production, indicating that the observed effects of extracellular Na+-deprivation were unrelated to the Na+/Ca2+ exchanger in receptor-mediated Ca2+ influx, as previously hypothesized. LTBs production by thapsigargin-activated neutrophils was not affected by Na+ depletion, but was totally abolished in the presence of EGTA, suggesting that store depletion-driven extracellular Ca2+ influx is required for leukotriene synthesis and that this process is independent of Na+-deprivation. Exposure to Na+-free medium for the time of GM-CSF priming led to a significant decrease of intracellular pH values, suggesting a role of the Na+/H+ exchanger in intracellular Na+ depletion. Reducing the time of Na+-deprivation totally reversed the observed effect on LTBs production, resulting in enhanced, rather than inhibited, formation of LTBs. These results indicate that LTBs generation and [Ca2+]i rise in human neutrophils primed by GM-CSF and stimulated with fMLP is dependent on intracellular Na+ concentration, and, at variance with previously published results, unrelated to the Ca2+ influx through the Na+/Ca2+ exchanger.
KW - Calcium ion
KW - Leukotriene B
KW - Neutrophils
KW - Sodium ion
UR - http://www.scopus.com/inward/record.url?scp=1642579530&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=1642579530&partnerID=8YFLogxK
U2 - 10.1016/j.bcp.2003.09.019
DO - 10.1016/j.bcp.2003.09.019
M3 - Article
VL - 67
SP - 385
EP - 393
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
SN - 0006-2952
IS - 2
ER -