In-vivo measurement of Single Nephron Glomerular Filtration Rate in an early diabetic rat using confocal microscopy

Abstract

Conventional SNGFR (single nephron glomerular filtration rate) measurement by micropuncture needs sampling fluids from a glomerulus, proximal tubule and distal tubule. Thus in-vio measurement has been impossible. The purpose of this study was to demonstrate in-vivo measurement of SNGFR by confocal laser microscopy. We used early DM Wistar rats induced by tail vein streptozotocin injection. Under anaesthesia, the kidney was exposed. Tubules were observed with a confocal microscope and 10 kDa extrans conjugated with Texas Red was administered. The urinary flow volumes between any given two points were measured from the video images and were converted to volumes for 1 minute, SNGFR. The values were found higher in diabetic rats than in control rats (19.1± 0.2 nl/min, 28.1± 0.2 nl/min)( p<0.05). SNGFR values were in the same order of reported values by the conventional method. We were able to demonstrate the hyperfiltration in early diabetes by SNGFR under in-vivo conditions.