Issue release date: 12.11.2024
2Hacettepe University, Department of Biochemistry, Ankara, Turkey
3Kaohsiung Medical College, Department of Neurosurgery, Kaohsiung, Taiwan Objective: Damage to the vascular endothelium is considered to be an important factor in the development of cerebral vasospasm after subarachnoid hemorrhage. Studies have shown that hemolysate causes structural and functional injury in cultured cerebral endothelial cells. Mexilitine is an anti-arrhythmic drug that is widely used in the treatment of ventricular arrythmias, and is known to act as a sodium-channel blocker. However experiments have shown that this compound can also activate ATP-sensitive potassium channels and block calcium channels. Recent in vitro data from studies on liposomes indicate that mexilitine is also a potent antioxidant. The aim of this study was to investigate the potential protective effects of mexilitine on endothelial cells incubated in hemolysate.
Methods: Endothelial cells were isolated from the bovine middle cerebral artery, and primary cell cultures were incubated and passaged weekly. Immunohistochemical staining was used to detect factor VIII-related antigen and acetylated low-density lipoprotein labeled with 1,1'-dioctadecy 1-3 ,3,3' -tetramethylindo-carbocyanine perchlorate (Dil-Ac-LDL), and thus it was confirmed that the cells were endothelial cells. The cells were grown to confluence on coated gelatin plates, and were incubated with Dulbecco's modified Eagle medium. Two plates were kept as controls; two plates were treated with 10-4 M hemolysate only; two plates were treated with a combination of 10-4 M mexilitine and 10-4 M hemolysate; two plates were treated with 10-8 M mexilitine and 10-4 M hemolysate; and two plates were treated with 10-12 M mexilitine and 10-4 M hemolysate. The cells were exposed to these specific media for 3 days. Cellular morphology and density were observed throughout this period using reverse-phase microscopy.
Results: Treatment with 10-4 M hemolysate alone destroyed almost all cells within 3 days. In the presence of the same concentration of hemolysate (10-4 M), 10-8 M or 10-12 M mexilitine preserved the cells' cobblestone appearance and number. However, addition of 10-4 M mexilitine had a deleterious effect. This concentration caused cytoplasmic vacuolization and transformation to spindle-shaped cell morphology.
Conclusion: Mexilitine's unique and diverse activity profile suggests that this agent might help prevent the endothelial cell damage caused by hemolysate after subarachnoid hemorrhage. The ability to stop this damage is a key factor in limiting cerebral vasospasm. The results proved that low-dose mexilitine treatment can prevent the structural and functional endothelial damage caused by hemolysate.
Keywords : Cerebral vasospasm, ion channels, lipid peroxidation, mexilitine, subarachnoid hemorrhage