The effect of dopamine on the intraocular pressure and pupil of the rabbit eye.

The presence of a dopamine-specific receptor that can influence intraocular pressure in the rabbit eye is suggested by these experiments: intravitreal, systemic, or topically administered dopamine solutions can produce a decrease in intraocular pressure that is dose-dependent. In high doses the decrease in intraocular pressure is accompanied by mydriasis, and alpha-adrenergic pupillary response. This alpha-response may be caused by dopamine as a direct, but weak alpha-stimulator or by displacement of norepinephrine onto the receptor from its storage site. At lower doses the decrease in intraocular pressure occurs in the absence of mydriasis and in spite of blockade of beta-adrenergic receptors. Further, a specific dopaminergic blocker, haloperidol, prevents this decrease in intraocular pressure. The decreases are small, but reproducible and suggest that dopamine can influence the adrenergic regulation of intraocular pressure.