Abstract
Purpose: :
To investigate effect of intravenously administrated two calcium channel blockers (CCBs), nilvadipine and lomerizine, on the local circulation in the optic nerve head (ONH) in hemilateral experimental glaucoma monkeys. Nilvadipine is a highly lipophilic agent that easily penetrates the central nervous system and lomerizine is an agent with relatively central nervous system specific vasodilating and little systemic hypotensive effect.
Methods: :
Nilvadipine (0.001mg/kg), lomerizine (0.01mg/kg), and solvent including ethanol and polyethylene glycol (control) were intravenously administrated to 9 monkeys with hemilateral experimental glaucoma induced by laser cautery in the trabecular meshwork in one eye of each monkey. The ONH circulation was analyzed as tissue blood velocity by the laser speckle method and compared between experimental glaucoma and contralateral normal eyes under systemic anesthesia. Intraocular pressure (IOP) and blood pressure were also monitored for 60 minutes after the drug administration. All procedures in the study were conducted in compliance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.
Results: :
The ONH circulation was significantly increased (P<0.05) in the normal untreated eyes by maximum of 12-13% compared to the baseline values at 10 minutes after the administration of both CCBs, while that effect was significantly attenuated in the contralateral experimental glaucoma eyes down to 5-6% increase and there was a significant difference between the ONH circulation changes in both eyes (P<0.05). IOP showed significant decrease (P<0.05) at 60 minutes after administration of both CCBs while blood pressure was not significantly changed. The ONH circulation was not significantly changed (P>0.05) in both eyes and blood pressure remained unchanged after intravenous administration of the solvent (control), while IOP showed similar significant decrease (P<0.05) suggesting that the IOP decrease was attributed to an effect of systemic anesthesia, not the CCBs.
Conclusions: :
Intravenously administrated CCBs, nilvadipine and lomerizine, significantly increase the ONH blood flow in monkey eyes probably by local vasodilating effect and that was attenuated in experimental glaucoma eyes.
Keywords: blood supply • optic nerve • neuroprotection