In vivo visualization of characteristics of renal microcirculation in hypertensive and diabetic rats

We developed a videomicroscope system with a charge-coupled device camera a nd evaluated it in the investigation of the glomerular microcirculation in normal [Wistar-Kyoto (WKY)], spontaneously hypertensive (SHR), and streptoy otocin-induced diabetic rats (STZ). In W-Ky, the diameter of the afferent a rterioles (Af) was 11.9 +/-0.7 mum and that of the efferent arterioles (Ef) was 8.9 +/-0.7 mum. Af and Ef in each glomerulus could be visualized simul taneously with continuous recording of blood pressure and renal blood flow. In SHR, Af diameter was constricted to similar to 60% of that in WKY. A do se-dependent dilation of Af and Ef was observed after administration of bar nidipine (1-10 mug/kg iv), a calcium channel antagonist, in all three group s. No change was seen in the Af-to-Ef diameter ratio (Af/Ef ratio) in WKY. In SHR, the Af/Ef ratio increased significantly because of the marked dilat ion of Af after barnidipine administration. In contrast, barnidipine dilate d Ef in STZ, causing a significant reduction in the Af/Ef ratio. This syste m can analyze in vivo glomerular microcirculation and systemic macrocircula tion simultaneously, allowing more direct investigation of the characterist ics of and acute changes in glomerular microcirculation in pathological ani mals.