Effects of selective dopamine-1 receptor activation on intraocular pressure in man

Abstract

The lack of specific agonists and antagonists has, until recently, precluded investigation of a role for dopamine receptors in the control of intraocular pressure. In the present study, we have examined the effects of fenoldopam, a novel selective dopamine 1 (DA 1) receptor agonist, on intraocular pressure, in eight healthy human volunteers. Fenoldopam, infused intravenously at 0·5 μg kg −1 min −1, increased intraocular pressure from 14·6±0·9 to 17·6±1·4 mmHg ( P < 0·05) while a control saline infusion had no effect. Pupil diameter and blood pressure did not change. In the same subjects, i.v. norepinephrine or angiotensin II both increased intraocular pressure—from 13·8±1·4- to 17·6±1·4 mmHg and from 13·4±1·3- to 17·5±1·7 mmHg respectively ( P < 0·05), and mean arterial pressure by about 20 mmHg. These data suggest that: (1) DA 1 receptor activation can modulate intraocular pressure; (2) the intraocular pressure effects of the DA 1 receptor agonist, fenoldopam, are independent of changes in systemic blood pressure, in contrast to those of norepinephrine or angiotensin II where intraocular and systemic blood pressures increase in parallel; (3) the ability of a DA 1 receptor antagonist to lower intraocular pressure merits investigation.