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.