Proteolytic Enzymes. HI. Circulating Esterase Activities after Parenteral Trypsin and Chymotrypsin in Rabbits. ∗

Summary

Inhibition of trypsin and chy-motrypsin by plasma has been studied using ester substrates. The amount of inhibition measured was low compared to that reported in the literature using protein substrates, and permitted the measurement of enzyme concentrations in plasma of the order of 10 μg/ ml. Intravenous injection of trypsin and chymotrypsin to rabbits resulted in measurable circulating esterase activity, which persisted, in the case of chymotrypsin, up to an hour after injection. No activity was detected following intramuscular trypsin, however, and no detectable increase over a small spontaneous esterase activity was noted following intramuscular chymotrypsin. Thus, it appears that the anti-inflammatory effect noted following intramuscular injection of these enzymes is probably not mediated by their systemic absorption.