The relationship between kidney and urinary kininogenase

Abstract

1 . Rat kidneys which were perfused with saline contained both kininogenase (KGA) and kininase activity. These activities were separated by gel filtration on a Sephadex G-100 column. The kininase activity was excluded from the column whereas the KGA activity was retained. Kidney KGA activity was primarily found in the sedimentable fraction of the homogenate. 2 . The kidney KGA activity was compared with the urinary KGA activity, and the following properties were found to be the same: molecular dimension, pH optimum, effect of inhibitors, and ability to liberate kinins from kininogens. 3 . A urinary sample collected over 24 h contained about 8 times the KGA activity found in the corresponding kidneys at the end of the collection period. The urine: kidney ratio for alkaline phosphatase was about 0.01. 4 . The ability of kidney and urinary samples to hydrolyse N-α-benzoyl-l-arginme ethyl ester (BAEE) at pH 8.5 paralleled the KGA activity.