1. In male mice without kidneys and submaxillary, as well as sublingual, glands aggressive behaviour causes a vast release of renin [J. Bing & K. Poulsen (1979) Acta Physiologica Scandinavica, 107, 251–256].
2. This resulted in about an 800-fold increase in plasma renin concentration from the control level of 0.52 (range 0.15-0.8) Goldblatt unit (G.U.) × 10−3/ml to 430 (range 300–500) G.U. × 10−3/ml after aggression.
3. The aggression-provoked renin fulfil all the criteria so far studied for being active renin, identical with normal mouse plasma renin and pure submaxillary mouse renin.
4. It generates angiotensin I with renin substrate and Km (1.2 μmol/l) is the same. It is neutralized by pepstatin but not by inhibitors of metallo-, thiol and serine proteinases, indicating that it is an aspartate proteinase (acidic proteinase).
5. It is a 40 000-mol.wt. renin, which has full enzymatic activity with a specific enzymatic activity of 0.32 G.U./μg, identical with that of normal plasma renin.
6. Its enzymatic activity is neutralized by a specific antibody against pure submaxillary renin. It is measurable in the direct renin radioimmunoassay with a dilution curve which parallels that of the standards. It demonstrates complete antigenic identity with pure submaxillary renin in crossed immunoelectrophoresis.
7. Its origin is unknown.