Response to Vonodote in the Robbit

The authors examined the influence of intravenously administered sodium ortho-vanadate upon the intraocular pressure (IOP) of the albino rabbit. Vanadate was administered by intravenous injection and the IOP was measured by applanation tonometry. Vanadate (2 mg/kg) caused a marked reduction of IOP which lasted for several hours. Pretreatment with systemic reserpine 24 hr prior to vanadate administration markedly diminished ocular hypertensive response to vanadate. Similarly, systemic treatment with propranolol prevented the IOP-lowering effect of vanadate. In addition, propranolol administered during the course of the vanadate-induced hypotensive response caused the IOP to return to a level close to the control value. The IOP-lowering effect of vanadate appeared to be unrelated to cardiovascular changes; vanadate was observed to have no significant influence upon the blood pressure of anesthetized animals even though the IOP was markedly reduced. On the basis of these experiments, the authors suggest that adrenergic mechanisms contribute to the IOP-lowering effect of vanadate. Invest Ophthalmol Vis Sci 26:1442-1445, 1985