Genetic heterogeneity and differences in glomerular hemodynamics between inbred colonies of Munich-Wistar rats

DNA fingerprint analysis and renal micropuncture studies were performed in Munich-Wistar rats purchased from Harlan Industries and Simonsen Laboratories to determine whether these rats are genetically heterogeneous and exhibit differences in glomerular hemodynamics. RBF and GFR were similar in rats from both colonies. Glomerular capillary pressure was lower in rats from the Harlan colony (46 +/- 2 mm Hg) than in those from the Simonsen colony (56 +/- 2 mm Hg). The low glomerular capillary pressure in the Harlan rats was primarily due to a lower postglomerular vascular resistance. The estimated whole-kidney ultrafiltration coefficient (Kf) was significantly greater in the rats obtained from the Harlan colony than in those obtained from the Simonsen colony (0.12 +/- 0.03 versus 0.05 +/- 0.01 mL/min/g kidney wt/mm Hg). The DNA fingerprints of the Simonsen rats were different from those of the Harlan rats. These results provide evidence of physiologic and genetic heterogeneity between commercially available inbred strains of Munich-Wistar rats in the United States and suggest that comparison of results with Munich-Wistar rats from different sources may be more difficult than previously recognized.