HISTOPATHOLOGICAL CHANGES IN KIDNEYS OF RABBIT EXPOSED TO HIGH NITRATE IN DRINKING WATER

Background: In India, especially in Rajasthan people drink water containing high level of nitrates and concentration up to 500 mg of nitrate ion per liter is not unusual. The ingested nitrate is converted to nitrite in the digestive system and absorb in blood causing methemoglobinemia. The peak of methaemoglobin is observed at 45-95 mg/liter of nitrate concentration in water.. Aims and Objects: To find out the correlation between drinking water nitrate concentration and histopathological changes in kidneys of rabbits of different groups. Materials and Methods: An experimental study was conducted in 10 rabbits between three and half month to four month of age having weight ranging 1.310 kg to 10720 kg. Five groups A, B, C, D and E were formed having two rabbits in each group. The control group A was administered water orally having 06 mg/liter. Group B to E (experimental groups) were administered water orally having concentration of 100mg/liter, 200mg/liter, 400mg/ liter & 500mg/liter of nitrate respectively for 120 days. Then all rabbits were anaesthetized & sacrificed according to guidelines of ICMR and kidneys were removed & processed for paraffin sections. Hemotoxyllin and eosin staining was done for microscopic observations. Results: During experiment, animals were lethargic on 75th day .Intake in quantity of food and water was not altered in the rabbits. Rabbits of all group i.e. A to E showed continuous increase in heart rate (up to 218/ minute in group E) and respiration rate (up to 84/minute in group E) respectively. The microscopic study of kidney showed focal collection of lymphocytes in interstitial tissue, particularly in pericapsular area of kidney which appeared in rabbits of group B. The changes were more pronounced in group C &D in the form of focal collection of plasma cells. The hyaline and cellular casts were observed in proximal & distal tubules which started appearing in animals of group C. The congestion of blood vessels and damaged tubular epithelium were observed in tubules of group E rabbits. Discussion and Conclusion: The Results occurred possibly due to cytochrome b5 reductase activity and its adaptation with increasing water nitrate concentration to compensate methaemoglobinemia.