VISUALIZATION OF RENAL MICROCIRCULATION IN ISOLATED MUNICH-WISTAR RATKIDNEYS - EFFECTS OF ENDOTHELIN-1 ON RENAL HEMODYNAMIC ACTIVITY

The aim of the present study was to visualize the superficial glomerul i of the Munich-Wistar (MW) rat and to characterize the responses of t he renal microvasculature to endothelin-1 (ET-1). We first examined th e distribution of superficial glomeruli of the MW rat compared to that in a control strain (Wistar rat). Secondly, we examined the effects o f ET-1 on the renal microcirculation of the MW rat. The right kidney w as perfused with a Krebs-Ringer solution containing fluorescein isothi ocyanate dextran (FITC-dextran) and was visualized under an epi-illumi nated fluorescence microscope system. Changes in perfusion pressure an d diameter of the microvessels accompanying the administration of ET-1 (10 fmole-300 pmole) were measured. The number of superficial glomeru li was greater in the MW rat than in the Wistar rat. ET-1 had long-las ting and dose-dependent presser effects. Perfusion pressure showed a 3 .5-fold increase compared with the control, and the afferent arteriole s showed greater dose-dependent vasoconstriction than the efferent art erioles. These findings suggest that the MW rat is a useful animal mod el for the study of renal microcirculation and that the renal microcir culation is extremely sensitive to ET-1.