Appearance of Enzymes in Plasma or Urine Following Renal Injury

The present study evaluates the relevance of plasma enzyme activityin the quantitative assessment of renal injury. In a caninemodel, enzyme release from kidneys to plasma and urine was studiedfollowing an artificial parenchymal enzyme infusion in healthyand ischaemic kidneys. The cumulative enzyme activity in plasmaand urine was calculated. Within 1 h of the start of the infusion,80% of the infused enzyme was recovered in plasma, whereas urinaryaccumulation was negligible. A similar enzyme distribution betweenthese compartments was obtained if the kidneys were ischaemicallydamaged before the start of the infusion. Thus enzymes releasedinto the renal cortical interstitium are very rapidly transportedto the vascular system and are quantitatively recovered in plasma.Experimental renal infarction revealed that cell death due toischaemia also resulted in enzyme accumulation in plasma.