Turnover of¹²⁵I-labelled tissue kallikrein following intraduodenal or intravenous administration

Abstract

The use of tissue kallikrein as an oral drug appears, therefore, to be useless. Tissue kallikrein released into plasma seems to be quickly bound to a protein with a mol wt of 67 kDa, probably kallistatin or Protein C inhibitor, but some tissue kallikrein seems to be unbound and may have some physiological or pathophysiological action. The unbound tissue kallikrein is, at least partly, cleared from the circulation by the kidneys, and tissue kallikrein in the urine may partly be derived from plasma.