Studies on Heme α-Methenyl Oxygenase

NO•, CO and•OH Endogenous soluble guanylyl cyclase-activating factors

Several low molecular weight compounds are capable of activating soluble guanylyl cyclase. Recent evidence suggests that some of these are formed under physiological conditions: the nitric oxide radical, carbon monoxide and the hydroxyl radical. Thus, multiple signal transduction pathways appear to exist that form a family of guanylyl cyclase activating factors and thereby regulate the intracellular cyclic guanosine 3',5'-monophosphate level.

Prevention of hemoglobinuria by administration of haptoglobin

This report describes the role of haptoglobin in preventing hemoglobinuria. In rabbits, human haptoglobin administered i.v. worked preventively against the development of hemoglobinuria in spite of the presence of a large amount of hemolysate containing free hemoglobin. More specifically: (1) the kidney did not present a dark brown color, (2) the deposition of iron in the kidney was significantly less than that in the same organ of rabbits given hemolysate only, and (3) the microangiographic and histological findings of the kidney were close to normal patterns. From the above it may be concluded that the administration of haptoglobin is effective for the prevention of hemoglobinuria and subsequent renal damage.