Mobilization of intracellular calcium by substance P in a human astrocytoma cell line (U-373 MG).
Variations in intracellular free calcium concentration (delta[Ca2+]i) were measured in intact and isolated human astrocytoma cells (U373 MG) loaded with fura-2 acetoxymethylester. Microperfusion of 50 nM substance P (SP), applied for 1 s, increased [Ca2+]i by 351 nM from a stable basal level of [Ca2+]i of 26 nM. The peak delta[Ca2+]i induced by SP was dose dependent with a threshold of 10(-3) nM, an ED50 of 1.3 nM and a maximal effect for concentrations of SP greater than 100 nM. The NK1 receptor agonist, [Sar9Met(O2)11]SP, mimicked the effect of SP, while the NK2 and NK3 selective receptor agonists, [N1(10)]NKA(4-10) and senktide, respectively, had no effect. The delta[Ca2+]i induced by SP was unaffected by 100 microM cadmium or by removal of extracellular calcium ions. Caffeine up to 30 mM had no effect on [Ca2+]i. In contrast, thapsigargin increased resting [Ca2+]i by 92 nM and reduced the delta[Ca2+]i induced by SP. A pertussis treatment (500 ng/ml-24 h) did not modify the delta[Ca2+]i induced by SP. We conclude that SP, acting on a NK1 receptor, mobilizes cytosolic calcium from an intracellular calcium pool which can be partially depleted by thapsigargin.
Bordey
A
A
Institut de Physiologie (URA 1446 CNRS), Université Louis Pasteur, Strasbourg, France.
Feltz
P
P
Trouslard
J
J
D001254:Astrocytoma / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D016257:Fura-2; D006801:Humans; D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1 / Q000819:agonists; D018041:Receptors, Neurokinin-2 / Q000819:agonists / Q000037:antagonists & inhibitors; D018042:Receptors, Neurokinin-3 / Q000819:agonists / Q000037:antagonists & inhibitors; D013373:Substance P / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1; D018041:Receptors, Neurokinin-2; D018042:Receptors, Neurokinin-3; D010566:Virulence Factors, Bordetella; D013373:Substance P; D002118:Calcium; D016257:Fura-2