Renal Function and Hemodynamic Study in Obese Zucker Rats

OBJECTIVES: To investigate the renal function and hemodynamic changes in obesity and hyperinsulinemia which are characteristics of type II diabetes. METHODS: Studies were carried out in two groups of female Zucker rats. Group 1 rats were obese Zucker rats with hereditary insulin resistance. Group 2 rats were lean Zucker rats and served as controls. In comparison with lean Zucker rats, obese Zucker rats exhibited hyperinsulinemia but normoglycemia. Micropuncture studies and morphologic studies were performed in these rats. RESULTS: Functional studies showed that obese Zucker rats exhibited increases in kidney weight and GFR(obese Zucker, 1.23±.07)ml/min; lean Zucker, 0.93±.03ml/min). Micropuncture studies revealed that the increase in GFR in obese Zucker rats was attributable to the increases in the single nephron plasma flow rate and glomerular transcapillary hydraulic pressure. The glomerular ultrafiltration coefficient was the same in both groups. Morphologic studies revealed that the increase in GFR in obese Zucker rats was associated with an increase in glomerular volume. CONCLUSIONS: These results suggest that obesity and hyperinsulinemia, which are the characteristics of type II diabetes, can be associated with glomerular hyperfiltration and glomerular capillary hypertension.