Effects of dopamine agonists and antagonists on pulsatile blood flow of ocular hypertensive rabbits.

It has been reported that some dopamine antagonists can suppress the intraocular pressure and can increase the blood flow in the retina and choroid. Therefore, several dopamine antagonists and agonists were studied to determine if they can increase the ocular pulsatile blood flow in ocular hypertensive rabbits with the intraocular pressure raised artificially to 40 mm Hg. It was found that numerous dopamine antagonists including loxapine, moperone, domperidone, haloperidol and metoclopramide increased pulsatile blood flow for 49-110%, 95-155%, 72-86%, 60-114%, and 39-139%, respectively. Floropipamide reduced the ocular pulsatile blood flow for 18% at 90 min and 10% at 120 min. Chlofluperol produced biphasic action on pulsatile blood flow by significantly reducing it initially at 60 min (-49%) and then markedly increasing it at 180 min (91%). In case of dopamine agonists, neither dopamine nor bromocriptine affected the pulsatile blood flow significantly. These results indicate that some of dopamine antagonists could be used to lower the intraocular pressure and to increase the ocular pulsatile blood flow as well.