A COMPARATIVR STUDY OF ENZYMATIC STAINING REACTIONS IN THE RAT KIDNEY WITH NECROBIOSIS INDUCED BY ISCHEMIA AND NEPHROTOXIC AGENTS (MERCUHYDRIN AND DL-SERINE)

Enzymatic staining reactions for the demonstration of succinic dehydrogenase, DPN diaphorase, esterase, glucuronidase, nonspecific alkaline and acid phosphatase, phosphatase at pH 7.2, glucose-6-phosphatase, 5-nucleotidase and adenosine triphosphatase were applied to rat kidneys in which necrobiosis was induced by either the ligation of renal vessels or the administration of the nephrotoxic substances dl-serine and Mercuhydrin. Frozen sections of fresh and formalin-fixed tissues were used throughout. The distribution patterns of these enzymes found in the normal rat kidney were consistent and in agreement with previous observations. The staining pattern of adenosine triphosphatase at pH 7.2 was distinetly different from that of 5-nucleotidase and nonspecific phosphatase.

Following occlusion of the blood supply, necrobiotic changes developed relatively slowly. An observation apparently so far not recorded in the literature, is the occurrence of protruded proximal convoluted tubules in the lumen of Bowman's capsules. Nephrotoxic drugs lead to a rapidly developing coagulation necrosis in proximal convoluted tubules within a few hours. Without exception, diminution of enzymatic activity occurred later in ischemic as compared to toxic necrosis.

Definite differences in the histochemically demonstrable enzymes were noticed in cells undergoing necrobiosis. Non-specific alkaline and acid phosphatase and phosphatase at pH 7.2, esterase and 5-nucleotidase remained at least partially active in cells made necrotic by all procedures. The oxidative enzymes succinic dehydrogenase and DPN diaphorase were more completely inactivated by toxic as compared to ischemic necrosis. The reverse was true for adenosine triphosphatase, glucuronidase and glucose-6-phosphatase. Of all enzymes tested, succinic dehydrogenase was the most sensitive indicator of nephrotoxic cell damage, since distinct inactivation occurred with both dl-serine and Mercuhydrin within 30 to 60 minutes.