Effects of kallidinogenase on ocular tissue circulation in rabbits

The purpose of this study is to evaluate the effects of kallidinogenase, a tissue kallikrein, on tissue circulation in the optic nerve head (ONH), choroid and retina. Kallidinogenase (1.0 IU/kg) or saline was injected intravenously into urethane-anesthetized rabbits, and the normalized blur value (NB), a quantitative index of in vivo tissue blood velocity, was measured in the ONH, choroid and retina before and for 90 minutes after injection, using the laser speckle method. The difference in NB values in the kallidinogenase group was significantly higher compared with that in the control group in the choroid (p < 0.05) and retina (p < 0.05, ANOVA of repeated measurements). In the ONH, however, there was no significant difference between the kallidinogenase group and the control group except transient increment 10 min after drug administration (p < 0.01, unpaired t-test). On the other hand, systemic condition parameters and intraocular pressure showed no intergroup difference significantly except for a transient decrease in blood pressure and increase in pulse rate in the kallidinogenase groups. Kallidinogenase increased blood velocity, and probably blood flow, in the choroid and retina of rabbits.