Arachidonic acid induces [Ca2+]i oscillations in smooth muscle cells from human airways.
The role of phospholipase A2 (PLA2) in mediating agonist-stimulation of bronchial contraction has not yet been studied at a cellular level. The aim of the present work was to examine the Ca2+ signal elicited in human bronchial smooth muscle cells by exogenous arachidonic acid (AA), a first product of PLA2 activity. To study the effect of AA (2-20 microM) on [Ca2+]i, a single cell video imaging technique was used. AA induced various patterns of [Ca2+]i increase; most frequently, [Ca2+]i oscillations were observed. The amplitude of [Ca2+]i repetitive peaks, but not the frequency, was dependent on AA concentration. In the absence of external Ca2+, AA evoked a slower and reduced transient increase in [Ca2+]i. It is concluded that AA or some of its metabolites release Ca2+ from intracellular stores and that a contribution of extracellular Ca2+ is essential for [Ca2+]i oscillations.
Institut de Physiologie, Fribourg, Switzerland.
J
J
Durand
N
N
Marmy
D016718:Arachidonic Acid / Q000494:pharmacology*; D001980:Bronchi / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016084:Bronchoconstriction / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D015398:Signal Transduction / Q000502:physiology
D016718:Arachidonic Acid; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium