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Department o f Zoology, University o f Kuwait, P.O. Box 5969, Kuwait

ABSTRACT

Enzyme histochemical studies were carried out on the head and trunk kidneys of the mudskipper Periophthalmus koelreuteri. The enzymes investigated were succinate dehydrogenase (SDH), NAD-linked malate dehydrogenase (MDH),ل-glycerophosphate dehydrogenase (ل-GPDH), NADP-linked isocitrate dehydrogenase (ICDH), NAD-linked lactate dehydrogenase (LDH), NADP-linked glucose-6-phosphate dehydrogenasc (G6PDH), nonspecific esterases and adenosine triphosphatase (ATPase). Dehydrogenase activities were negligible in renal corpuscles and weak in distal tubules, but were generally high in proximal tubules. Activities of mitochondria1 bound enzymes (SDH, MDH and ل-GPDH) indicated that more mitochondria were found in the proximal tubules than in the distal tubules, whereas LDH as representative of glycolytic pathway was weakly tomoderately reactive in both segments. Non-specific esterases were found in the lysosomal system of PI tubule cells and in the melano-macrophage centres. ATPase activity was found in the renal corpuscle and was more active in the cytoplasm and basement membrane of the proximal tubules than in the distal tubules. The results imply the importance of the proximal tubule segment in osmoregulation and excretory activities of the kidney of Periophthalmus in the hyperosmotic environment of the Arabian Gulf.