Effect of lysine on hemolysis-induced kidney damage

The mechanism of kidney damage commonly seen in patients with intravascular hemolysis is not entirely clear. Injection of distilled water (4 ml within 5 seconds) into the carotid arteries of rats resulted in intravascular hemolysis leading to hemoglobinemia, hemoglobinuria, reduction in inulin clearance, and elevation of urine N-acetyl-beta-D-glucosaminidase (NAG) excretion. When the same experiment was repeated with simultaneous infusion of the positively charged amino acid lysine (30 mmol/L at 3.4 ml/hour), the inulin clearance was unchanged. Urinary NAG excretion was elevated but significantly lower than that in similar rats without lysine infusion. This suggested that lysine protected the kidney from the deleterious effect of hemolysis. Such protection was not observed when the neutral amino acid glycine was infused. Because positively charged but not neutral amino acids are known to inhibit renal protein reabsorption, the protective effect of lysine could be due to inhibition of hemoglobin reabsorption, which might be an important step in the pathogenesis of kidney damage.