title: The KCa3.1 blocker TRAM-34 reduces infarction and neurological deficit in a rat model of ischemia/reperfusion stroke.
abstract: Microglia and brain infiltrating macrophages significantly contribute to the secondary inflammatory damage in the wake of ischemic stroke. Here, we investigated whether inhibition of KCa3.1 (IKCa1/KCNN4), a calcium-activated K(+) channel that is involved in microglia and macrophage activation and expression of which increases on microglia in the infarcted area, has beneficial effects in a rat model of ischemic stroke. Using an HPLC/MS assay, we first confirmed that our small molecule KCa3.1 blocker TRAM-34 effectively penetrates into the brain and achieves micromolar plasma and brain concentrations after intraperitoneal injection. Then, we subjected male Wistar rats to 90 minutes of middle cerebral artery occlusion (MCAO) and administered either vehicle or TRAM-34 (10 or 40 mg/kg intraperitoneally twice daily) for 7 days starting 12 hours after reperfusion. Both compound doses reduced infarct area by ≈ 50% as determined by hematoxylin & eosin staining on day 7 and the higher dose also significantly improved neurological deficit. We further observed a significant reduction in ED1(+)-activated microglia and TUNEL-positive neurons as well as increases in NeuN(+) neurons in the infarcted hemisphere. Our findings suggest that KCa3.1 blockade constitutes an attractive approach for the treatment of ischemic stroke because it is still effective when initiated 12 hours after the insult.
authors.affiliation: Department of Pharmacology, Genome and Biomedical Sciences Facility, University of California, Davis, California 95616, USA.
authors.forename: Yi-Je
authors.initials: YJ
authors.lastname: Chen
authors.forename: Girija
authors.initials: G
authors.lastname: Raman
authors.forename: Silke
authors.initials: S
authors.lastname: Bodendiek
authors.forename: Martha E
authors.initials: ME
authors.lastname: O'Donnell
authors.forename: Heike
authors.initials: H
authors.lastname: Wulff
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000517:prevention & control*; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors*; D008262:Macrophage Activation / Q000502:physiology; D008264:Macrophages / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D017628:Microglia / Q000378:metabolism; D009422:Nervous System Diseases / Q000473:pathology / Q000517:prevention & control*; D018696:Neuroprotective Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010539:Permeability; D011485:Protein Binding; D011720:Pyrazoles / Q000493:pharmacokinetics / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*
chemical_list: D001798:Blood Proteins; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C491575:Kcnn4 protein, rat; D018696:Neuroprotective Agents; D011720:Pyrazoles; C411671:TRAM 34