Involvement of prostaglandin E(2) derived from enteric glial cells in the action of bradykinin in cultured rat myenteric neurons.
We characterized bradykinin (BK)-induced changes in the intracellular Ca(2+) concentration ([Ca(2+)]i) and membrane potential in cultured rat myenteric neurons using ratiometric Ca(2+) imaging with fura-2 and the whole-cell patch-clamp technique, respectively. BK evoked a dose-dependent increase of [Ca(2+)]i that was abolished by HOE 140, a B2 receptor antagonist but not by [Lys-des-Arg(9)]-BK, a B1 receptor antagonist. [Lys-des-Arg(9)]-HOE140, a B1 receptor agonist, failed to cause a [Ca(2+)]i response. Double staining with antibodies against the B2 receptor together with PGP9.5 or S100 indicated that B2 receptors were expressed in neurons and glial cells. The BK-evoked [Ca(2+)]i increase was suppressed by indomethacin, a non-selective cyclooxygenase (COX) inhibitor, and potentiated by prostaglandin E(2) (PGE(2)). The release of PGE(2) from cultured myenteric plexus cells was increased by BK. BK induced a large increase in [Ca(2+)]i in neurons when myenteric plexus cells were cultured at the high density but not at the low density, and caused a small increase in [Ca(2+)]i in neurons when proliferation of enteric glial cells was suppressed. BK evoked a slow and sustained depolarization in myenteric neurons, which was sensitive to indomethacin. These results indicated that BK caused a [Ca(2+)]i increase and depolarization in rat myenteric neurons through the activation of B2 receptors, which was partly associated with PGE(2) released from glial cells in response to BK. It is suggested that a neuron-glial interaction plays an important role in the effect of BK in the rat myenteric plexus.
Murakami
M
M
Laboratory of Pharmacology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, N18W9, Sapporo 060-0818, Japan.
Ohta
T
T
Otsuguro
K-I
K
Ito
S
S
D000818:Animals; D001920:Bradykinin / Q000378:metabolism* / Q000494:pharmacology; D065169:Bradykinin B1 Receptor Antagonists; D065094:Bradykinin B2 Receptor Antagonists; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002452:Cell Count; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D016257:Fura-2; D041981:Gastrointestinal Tract / Q000294:innervation / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009197:Myenteric Plexus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D043783:Receptor, Bradykinin B1 / Q000819:agonists / Q000378:metabolism; D043782:Receptor, Bradykinin B2 / Q000819:agonists / Q000378:metabolism*
D065169:Bradykinin B1 Receptor Antagonists; D065094:Bradykinin B2 Receptor Antagonists; D016861:Cyclooxygenase Inhibitors; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D015232:Dinoprostone; D001920:Bradykinin; D002118:Calcium; D016257:Fura-2