Polymorphonuclear invasion of the wounded rat cornea is quantitatively described. The inflammatory cells enter the wounded tissue during the 5th postoperative hour. They steadily increase in number until they reach a maximum between 24 and 36 hours and return to normal by about the 6th day.
Six hour wounds are used to evaluate the influence of topically applied drugs on the polymorphonuclear infiltration of the wounded area. Sodium salicylate is an effective inhibitor of polymorphonuclear invasion when it is used during the 2nd postoperative hour, but it is without effect when it is applied after this time. Soybean trypsin inhibitor prevents the invasion of polymorphonuclear cells when it is administered during the 2nd hour only, or the 3rd and 4th hours together, or the 5th and 6th hours together.
The results indicate that activation of a proteolytic enzyme (or enzymes) in the injured corneal tissue is an essential step leading to polymorphonuclear invasion.
During the first 2 postoperative hours the anti-inflammatory effects of both drugs are nearly identical and may reflect an inhibition of the same proteolytic reaction or some different but closely related reactions.