Extracellular ATP increases intracellular calcium in cultured adult Schwann cells.
We have previously reported that extracellular ATP causes a transient rise in intracellular calcium concentration ([Ca2+]i) in cultured Schwann cells derived from adult animals [Ansselin A. D. et al. (1994) Int. J. Neurosci. 74, 148]. In this study, the receptor mediating this response has been characterized. Established adult rat and rabbit Schwann cell cultures were loaded with fura-2 (acetoxymethyl ester, 10 micromol/l, 40 min, 37 degrees C). which indicated, by fluorescence imaging, a resting [Ca2+]i of 34.7 +/- 1.4 nmol/l (mean S.E., n=591). The cells were exposed to 100 micromol/l ATP, ADP, AMP, UTP and adenosine in defined medium for 1-2 min, and the change in [Ca2+]i was observed as a change in the Fura-2 ratio. Seventy-seven percent of adult rat Schwann cells (n=235) and 88% adult rabbit Schwann cells (n=356) responded to the presence of extracellular ATP (100 mmol/l) with a transient increase in [Ca2+]i (41 and 90 nmol/l from resting value, respectively), independent of the presence of [Ca2+]o. Calcium waves were observed in one experiment. The following order of agonist potency was observed: UTP= ATP>>ADP>AMP=adenosine. The agonists alpha,beta-methylene-ATP and 2-methylthio-ATP had a small effect on the cells, similar to AMP, and were mutually desensitizing. The ATP antagonist suramin blocked the response. We conclude that adult Schwann cells express a purinergic ATP receptor belonging to the G-protein-coupled P2u alpha subtype [O'Connor S. et al. (1991) Trends pharmac. Sci. 12, 137-141].
Ansselin
A D
AD
School of Anatomy, University of New South Wales, Australia.
Davey
D F
DF
Allen
D G
DG
D000227:Adenine Nucleotides / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D018613:Microscopy, Confocal; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism; D010641:Phenotype; D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012583:Schwann Cells / Q000187:drug effects / Q000378:metabolism*; D012584:Sciatic Nerve / Q000166:cytology / Q000187:drug effects
D000227:Adenine Nucleotides; D005456:Fluorescent Dyes; D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2