Azelnidipine exerts renoprotective effects by improvement of renal microcirculation in angiotensin II infusion rats.
BACKGROUND
Hypoxia-induced tubulointerstitial injury caused by loss of peritubular capillary (PTC) blood flow may be associated with progressive renal disease. Therefore, the maintenance of blood flow in PTCs may protect against loss of renal function. A long-acting calcium channel blocker, azelnidipine, has been shown to be useful in the treatment of progressive renal disease. However, its mechanism of action remains unclear. The aim of the present study was to elucidate whether azelnidipine maintains PTC blood flow and to compare it to nifedipine in its ability to improve tubulointerstitial injury caused by angiotensin II (AII) infusion in rats.


METHODS
PTC blood flow was initially monitored using a pencil-lens interval microscope before and after intravenous AII (30 ng/kg/min) infusion with or without azelnidipine (10 microg/kg/min). Next, Wistar rats were treated with chronic infusion of AII (500 ng/kg/min) via an osmotic minipump with or without azelnidipine (3 mg/kg/day, orally) or nifedipine (60 mg/kg/day, orally) for 14 days, and tubulointerstitial damage (PTC loss, interstitial fibrosis, tubular atrophy) was examined.


RESULTS
PTC blood flow was reduced after AII infusion but improved after a bolus injection of azelnidipine. Tubulointerstitial damage observed in chronically AII-treated kidneys was associated with hypoxic conditions, as indicated by the measurement of hypoxia biomarkers (intracellular hypoxyprobe-1 adducts). These tubulointerstitial injuries in AII-infused rats were more effectively reduced by azelnidipine than by nifedipine. The area showing hypoxic conditions in the kidney was also more reduced with azelnidipine than nifedipine treatment.


CONCLUSIONS
Azelnidipine may increase PTC blood flow and improve renal hypoxia and tubulointerstitial injury induced by AII infusion.
Fujimoto
Sohachi
S
Division of Nephrology, Department of Internal Medicine, Kawasaki Medical School, Kurashiki, Okayama, Japan.
Satoh
Minoru
M
Nagasu
Hajime
H
Horike
Hideyuki
H
Sasaki
Tamaki
T
Kashihara
Naoki
N
D000804:Angiotensin II / Q000008:administration & dosage; D000818:Animals; D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D004095:Dihydropyridines / Q000627:therapeutic use*; D007262:Infusions, Intravenous; D008297:Male; D008833:Microcirculation / Q000187:drug effects*; D009395:Nephritis, Interstitial / Q000503:physiopathology* / Q000517:prevention & control*; D009543:Nifedipine / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D012079:Renal Circulation / Q000187:drug effects*
D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D000804:Angiotensin II; D001383:Azetidinecarboxylic Acid; D009543:Nifedipine; C061679:azelnidipine