Formation of Kinins in Plasma & Tissues

FORMATION OF KININS IN PLASMA & TISSUES

The pathway for the formation and metabolism of kinins is shown in Figure 17–4. Three kinins have been identified in mammals: bradykinin, lysylbradykinin (also known as kallidin), and methi-onyllysylbradykinin. Each contains bradykinin in its structure.Each kinin is formed from a kininogen by the action of a dif-ferent enzyme. Bradykinin is released by plasma kallikrein, lysyl-bradykinin by tissue kallikrein, and methionyllysylbradykinin by pepsin and pepsin-like enzymes. The three kinins have been found in plasma and urine. Bradykinin is the predominant kinin in plasma, whereas lysylbradykinin is the major urinary form.