The participation of the platelet in the vascular response to endotoxemia in the rabbit eye.

Platelet depletion by a specific goat antirabbit platelet antiserum profoundly affected the response of the ocular blood vessels to intravenous endotoxin. The altered permeability of the vessels of the iridial portion of the ciliary processes in the thrombocytopenic animals was reduced by 50% at 1(1/2) hours and by 30 to 58% at 4 hours after endotoxin administration. Intravascular fibrin at the 4-hour period could be eliminated by a properly timed platelet depletion. By preventing platelet aggregations and fibrin formation, the permeability alteration could be reduced by 66% and the usual stromal hemorrhages practically eliminated. Underlying these effects of the platelet was evidence of a vascular trauma unrelated to platelet activity and probably dependent to some extent on adrenergic stimulation. Platelet aggregation and/or fibrin formation had to be superimposed on the underlying vascular trauma to produce endothelial denudation.