QUANTITATIVE MORPHOLOGY OF THE RAT-KIDNEY DURING DIABETES-MELLITUS AND INSULIN-TREATMENT

A morphometric study was performed on moderately hyperglycaemic strept ozotocin diabetic rats after 10 and 50 days of diabetes, and on groups of rats that, after initial hyperglycaemia for 50 days, were insulin treated for 2 h or for 5, 15 or 38 days. A group of hyperglycaemic dia betic animals were fasted for 18 h. Another group of rats had acute hy perglycaemia induced by intravenous glucose injection. After 10 and 50 days of diabetes, kidney weight was increased by 55 and 93 %. Glomeru lar volume, tubule length, and tubular and interstitial volume increas ed in diabetic animals compared with controls. After 4 h insulin treat ment, the kidney weight was 20 % decreased; after 5 days it was 31 % d ecreased. After 38 days the kidney weight was still 26 % greater than in controls. In diabetic animals, 18 h fasting induced a 30 % decrease in kidney weight. In normal animals, acute hyperglycaemia induced a 2 2 % increase in kidney weight. Volume fractions of most kidney structu res remained similar in ail groups. However, the glomerular volume fra ction was smaller during kidney enlargement, and the tubular volume fr action was larger after induced hyperglycaemia compared with controls. In conclusion, high blood glucose levels in diabetic and normal anima ls are associated with increased kidney weight. In hyperglycaemic diab etic animals, normalization of blood glucose after insulin treatment o r fasting was followed by a decrease in kidney weight.