In vivo visualization of glomerular microcirculation and hyperfiltration in streptozotocin-induced diabetic rats.
OBJECTIVE
Knowledge of glomerular structural and hemodynamic changes in vivo is still limited under diabetic conditions. In this study, we examined the alterations in glomerular structure and permeability of macromolecules and the effects of telmisartan using a confocal laser microscope.


METHODS
Diabetes was induced by injecting streptozotocin. After 4 and 8 weeks, the filtration and permeability of differently sized compounds across the glomerular capillaries were visualized using a confocal laser microscope by injecting 500-kilodalton and 40-kilodalton dextran. At 7 weeks, some diabetic rats were treated with telmisartan for 1 week. The permeation of the 40-kilodalton dextran across the glomerular capillaries into Bowman's space was quantified. Glomerular volume, diameters of the afferent and efferent arterioles, and glomerular permeability were compared.


RESULTS
Glomerular volume was significantly increased in the diabetic rats, and there was heterogeneity in the glomerular volumes. The diameter ratio of the afferent to efferent arterioles significantly increased, and there was increased glomerular permeability in the diabetic rats compared with the control rats. Telmisartan treatment reduced glomerular permeability without affecting glomerular volume.


CONCLUSIONS
These data showed that glomerular hyperfiltration started from the early phase of diabetes, accompanied by dilatation of afferent arterioles and glomerular hypertrophy.
Satoh
Minoru
M
Division of Nephrology, Department of Internal Medicine, Kawasaki Medical School, Kurashiki, Japan. msatoh@med.kawasaki-m.ac.jp
Kobayashi
Shinya
S
Kuwabara
Atsunori
A
Tomita
Naruya
N
Sasaki
Tamaki
T
Kashihara
Naoki
N
D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000503:physiopathology; D001562:Benzimidazoles / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D002199:Capillary Permeability / Q000187:drug effects / Q000502:physiology; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*; D003928:Diabetic Nephropathies / Q000188:drug therapy / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D005919:Glomerular Filtration Rate / Q000502:physiology; D007678:Kidney Glomerulus / Q000098:blood supply* / Q000187:drug effects / Q000473:pathology; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D036641:Microscopy, Fluorescence, Multiphoton; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000502:physiology; D000077333:Telmisartan
D047228:Angiotensin II Type 1 Receptor Blockers; D001562:Benzimidazoles; D001565:Benzoates; D000077333:Telmisartan