Effects of selective dopamine-1 receptor activation on intraocular pressure in man.
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 dopamine1 (DA1) receptor agonist, on intraocular pressure, in eight healthy human volunteers. Fenoldopam, infused intravenously at 0.5 micrograms kg-1 min-1, increased intraocular pressure from 14.6 +/- 0.9 to 17.6 +/- 1.4 mmHg (P less than 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 less than 0.05), and mean arterial pressure by about 20 mmHg. These data suggest that: (1) DA1 receptor activation can modulate intraocular pressure; (2) the intraocular pressure effects of the DA1 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 DA1 receptor antagonist to lower intraocular pressure merits investigation.
Karnezis
T A
TA
Committee on Clinical Pharmacology, University of Chicago, IL 60637.
Murphy
M B
MB
Weber
R R
RR
Nelson
K S
KS
Tripathi
B J
BJ
Tripathi
R C
RC
D000293:Adolescent; D000328:Adult; D000804:Angiotensin II / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D018818:Fenoldopam; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011680:Pupil / Q000187:drug effects; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000502:physiology; D017447:Receptors, Dopamine D1
D001552:Benzazepines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D000804:Angiotensin II; D018818:Fenoldopam; D009638:Norepinephrine