Role of proteases in hypercatabolic patients with renal failure.

Proteolytic enzymes exist in plasma ultrafiltrates, concentrated dialysates, and urine fractions of patients with posttraumatic acute renal failure (ARF), as well as in urine fractions of patients with nephrotic syndrome and in concentrated dialysates of patients or routine dialysis therapy (RDT). Differences in the digestion pattern of phosphorylase kinase suggest the existence on different proteases. Plasma trypsin-binding capacity is reduced in RDT patients and is markedly decreased in patients with posttraumatic ARF compared with healthy subjects. Protein catabolism of plasma fractions of patients with posttraumatic ARF is inhibited in vitro by alpha 2-macroglobulin. Urinary alpha 1-antitrypsin inactivates added kallikrein in urine fractions of patients with posttraumatic ARF or nephrotic syndrome. Proteases may also be involved in the disturbances of carbohydrate metabolism of uremic patients. The role of proteolytic degraded phosphorylase kinase, muscle contractile proteins, hormone receptors, or pancreas islets on the pathogenesis of altered carbohydrate metabolism in uremia is discussed.