The renal kallikrein-kinin system: a look at the controversies

Identification of rat urinary kinin as bradykinin

Bradykinin (BK)-like activity, which was detected by BK-enzyme-immunoassay, was purified from 80 ml of ureter urine of Sprague-Dawley rats by Sephadex G 25 chromatography, FPLC, and reversed phase HPLC. The purified kinin fraction showed the same retention time as authentic BK on HPLC and produced contraction of isolated rat uterus, the contraction being suppressed by a B2-antagonist Hoe140. There was no other kinin detected on the HPLC at the corresponding retention time to kallidin, arginyl-BK or T-kinin. The peptide showed an amino acid sequence identical to that of BK by amino acid sequence analysis.

A kallikrein-like enzyme in blood vessels of one-kidney, one clip hypertensive rats

Active and inactive kallikrein or a kallikrein-like enzyme are found in the aorta, vena cava, and tail artery and veins of the rat. We studied the concentration of vascular kininogenase in rats with one-kidney, one clip renovascular hypertension and in unilaterally nephrectomized normotensive rats. Six weeks after surgery, active and total vascular kininogenase activity (active plus trypsin-activated) was measured. Blood pressure was 212 +/- 4 mm Hg in the hypertensive rats (n = 33) and 120 +/- 1 mm Hg in the normotensive rats (n = 32) (p less than 0.001). Active kininogenase was lower in the hypertensive rats; although the difference was not significant in the thoracic aorta (56 +/- 8 versus 77 +/- 15), it was highly significant in the abdominal aorta (63 +/- 13 versus 167 +/- 17, p less than 0.001) and tail artery (48 +/- 8 versus 197 +/- 31, p less than 0.003). Total vascular kininogenase activity (active plus trypsin-activated) was lower in the hypertensive rats in all arteries examined: thoracic aorta (183 +/- 16 versus 380 +/- 38, p less than 0.003), abdominal aorta (565 +/- 61 versus 1,093 +/- 74, p less than 0.001), and tail artery (532 +/- 112 versus 1,243 +/- 135, p less than 0.003). Active kininogenase in the vena cava was higher in the hypertensive rats (213 +/- 56 versus 131 +/- 31); however, this difference was not statistically significant, whereas in the tail veins it was highly significant (1,803 +/- 221 versus 771 +/- 79, p less than 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)