Reduction of neuronal damage in ischemic stroke using a combination therapy of TMB-8 with L-arginine

Treatment with a combination of a calcium antagonist TMB-8 and NO donors, L-arginine and N alpha-benzoyl-L-arginine ethyl ester (BAEE) to prevent experimental ischemic stroke were studied in rats through the permanent occlusion of the middle cerebral artery and common carotid artery for 60 minutes. When the animals were treated with TMB-8, L-arginine, BAEE or NO synthetase inhibitor, nitro-L-arginine at time 0 of ischemia, the areas of neuronal necrosis were reduced by 98%, 99%, 99% and 89%, respectively. When these compounds were administered at 6 hrs after ischemia, the areas of neuronal necrosis were reduced by 91%, 96%, 86% and 81%, respectively. When TMB-8, L-arginine, BAEE or nitro-L-arginine were administered at 24 hours after ischemia, the necrosis areas were reduced less effectively by 80%, 89%, 77% and 60%, respectively. A combination with TMB-8 and L-arginine at time 0, 6 or 24 hr after ischemia resulted in the areas of necrosis being reduced by 99%, 99%, and 89%, respectively. Treatment with the combination of TMB-8 and BAEE at time 0, 6 or 24 hrs after ischemia, resulted in the areas of necrosis being reduced by 99%, 96%, and 82%, respectively. When the drugs were administered at 0 hr of ischemia, L-arginine, BAEE and nitro-L-arginine increased NO synthase activity in the ischemic cortex from 369 +/- 27 of ischemic control to 614 +/- 39, 511 +/- 32 and 406 +/- 16 respectively 1 days after stroke. TMB-8 was a potent agent in reducing intracellular calcium from the base line and blocking the elevation of calcium induced by KCl. The spectrin proteolysis protein, a calcium-activated proteolysis protein was also inhibited by TMB-8 in the ischemic cortex. These results indicated that a combination of TMB-8 and L-arginine is more effective in treating ischemic stroke by simultaneously reducing calcium-activated proteolysis and improving of cerebral blood flow than using TMB-8 or L-arginine alone.