title: Air bubble contact with endothelial cells in vitro induces calcium influx and IP3-dependent release of calcium stores.
abstract: Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50-150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway.
authors.affiliation: Dept. of Anesthesiology and Critical Care, Univ. of Pennsylvania, Philadelphia, 19104-4283, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Sobolewski
authors.forename: Judith
authors.initials: J
authors.lastname: Kandel
authors.forename: Alexandra L
authors.initials: AL
authors.lastname: Klinger
authors.forename: David M
authors.initials: DM
authors.lastname: Eckmann
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000388:Air; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D004618:Embolism, Air / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology; D047028:Macrocyclic Compounds / Q000494:pharmacology; D045423:Microbubbles / Q000009:adverse effects*; D009355:Neomycin / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D012430:Ruthenium Red / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D002121:Calcium Channel Blockers; D053496:Inositol 1,4,5-Trisphosphate Receptors; D047028:Macrocyclic Compounds; D010080:Oxazoles; D050916:TRPV Cation Channels; C511704:xestospongin C; D012430:Ruthenium Red; D015638:Cytochalasin D; D015759:Ionomycin; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D005682:Gadolinium; D010738:Type C Phospholipases; D009355:Neomycin; C038958:gadolinium chloride