effect of dopamine and its interaction with some drugs on the intraocular pressure of rabbits

ABSTRACT

The effect of dopamine on the intraocular pressure [IOP] of rabbit eye has been evaluated by electromanometric technique. Both intraocular pressure [IOP] and blood pressure [BP] were measured by manometry in anaethetised rabbits through cannulation of the anterior chamber and femoral artery respectively. This work was done as a trial to detect the type of receptors activated by dopamine in the eye. Injection of dopamine by intravenous infusion at a rate of 250 micro per minute for 20 minutes caused a significant reduction in the lOP which reached its maximum after two hours and the effect remained for four hours after stopping infusion. This ocular hypotensive effect of dopamine was blocked by the alpha-blocker phentolamine and possibly by chlorpromazjne which has an alpha-blocking and a dopaminergic blocking effects. On the other hand, the effect of dopamine was not affected by the dopaminergic blocker metoclopramide or by the beta blocker beta befunolol. From this study it could be concluded that the ocular hypotensive effect of dopamine on the rabbit eye may occur mainly through activation of alpha-receptors