The effects of ochratoxin A, a nephrotoxin, on various metabolic pathways in kidney cortex will be examined in order to elucidate its biochemical action in the proximal tubule. In these studies rats will be fed the toxin via a stomach tube with subsequent enzymatic analysis of kidney cortex tissue and evaluation of its gluconeogenic capacity by kidney slice technique. Similar experiments will be performed in liver tissue in order to see if the toxin's effects are selective. In addition to the enzymes of gluconeogenesis, those of glycolysis and ammoniagenesis, as affected by ochratoxin A, may be observed. Other experiments of this nature will be performed on ducklings, a species which exhibits a much lower LD 50 for the toxin than do rats.