| 12384249 |
Easton AS, Abbott NJ: Bradykinin increases permeability by calcium and 5-lipoxygenase in the ECV304/C6 cell culture model of the blood-brain barrier. Brain Res. 2002 Oct 25;953(1-2):157-69.
The blood-brain barrier (BBB) was modelled in this study using ECV304 cells in co-culture with rat C6 glioma cells, which resulted in elevated transendothelial electrical resistance (TEER). The inflammatory mediator bradykinin (1 microM) was studied and found to induce a fall in TEER; the link between this change and intracellular free calcium concentration ([Ca (2+)](i)) was then examined. 1 microM bradykinin produced a peak-plateau increase in [Ca (2+)](i). The peak showed desensitization and was dose dependent (over 0.1 nM to 1 microM). The [Ca (2+)](i) increase was blocked by the B (2) antagonist HOE 140 (1 microM) without effect from a B (1) agonist and antagonist. The plateau response was abolished in Ca (2+)-free solution containing 2 mM EDTA, and also by the Ca (2+) channel blockers lanthanum, La (3+) (10 microM), and SKF 96365 (100 microM). The store Ca (2+) ATPase inhibitor thapsigargin (1 microM) abolished the peak response. The putative phospholipase C inhibitors, U73122 (20 microM) and ETH-18-OCH (3) (100 microM), unexpectedly increased [Ca (2+)](i); after their application, bradykinin was ineffective. Agents without effect on Ca (2+) responses to bradykinin included the phospholipase A (2) (PLA (2)) inhibitor aristolochic acid (0.5 mM), cyclooxygenase inhibitor indomethacin (100 microM), 5-lipoxygenase inhibitor nordihydroguaiaretic acid, NDGA (100 microM), calphostin C (0.5 microM), L-NAME (1 mM) and nifedipine (10 microM). The fall in TEER from bradykinin was blocked by HOE 140, U73122 and thapsigargin combined with La (3+), and also by aristolochic acid and NDGA, but not indomethacin, calphostin C or L-NAME. U73122 increased TEER while ETH-18-OCH (3) reduced it. Thus bradykinin reduced TEER through B (2) receptor-linked release of Ca (2+) from thapsigargin-sensitive stores, leading to activation of PLA (2) and metabolism of arachidonic acid by 5-lipoxygenase. |
3(0,0,0,3) |