COMPARATIVE METABOLISM OF PLASMINOGEN GLYCOFORM-I AND GLYCOFORM-II INTHE ALLOXAN-DIABETIC RABBIT

The metabolism of plasminogen glycoforms I and II was measured in allo xan-induced diabetic and in age-matched control rabbits. Radiolabeled plasminogen I and II were degraded significantly more slowly in diabet ic compared with control rabbits; plasminogen II [half-time (T-1/2), 1 .31 days] was degraded faster than plasminogen I (T-1/2, 1.86 days) in diabetic rabbits and in control rabbits (T-1/2, 1.18 and 1.58 days, r espectively). From the catabolic rates and relative quantities in plas ma, we calculated that approximately four molecules of plasminogen II were degraded-for one molecule of plasminogen I in the diabetic and co ntrol rabbits. To verify this latter observation, plasminogen I and II production by diabetic rabbit livers was compared with that by the co ntrol livers in vitro. During perfusion with [H-3]leucine, H-3-labeled protein was released more slowly from diabetic than from control live rs, but no quantitative difference in total plasminogen yield between diabetic and control livers was found. Nevertheless, plasminogen II wa s produced 3.7 +/- 0.4 and 4.3 +/- 0.3 times faster than plasminogen I by diabetic-and control livers, respectively. Plasminogen metabolism in the diabetic rabbit did not differ qualitatively from that in the c ontrol rabbit except that catabolism was slowed.