オートラジオグラフィーによるラット腎の蓚酸分布と蓚酸カルシウム結晶付着部位の検討

Abstract

正常ラットにおけるthaw mount法を用いた14C-標識蓚酸の経時的腎ミクロオートラジオグラムでは, 投与された14C-標識蓚酸はその大部分が尿中に排泄された後も, 集合管上皮細胞内及びその周囲の間質に一時的に停滞することが観察され, この蓚酸の停滞が蓚酸カルシウム結石発症にかかわっていることが強く示唆された.事実, 過蓚酸尿症ラットにおいては, 集合管上皮細胞内及びその周囲の間質での蓚酸カルシウム結晶の析出沈着が最初に出現し, この析出沈着した結晶が次第に成長することが, X線分析を併用した14C-標識蓚酸腎ミクロオートラジオグラフィーにより証明された

To elucidate the intrarenal distribution of oxalate and to reveal the first site of calcium oxalate crystal fixation along the nephron, we carried out 14C-oxalate renal microautoradiography by the thaw mount method 30, 60 and 90 min after intravenous administration of 14C-oxalate, in normal rats and in hyperoxaluric rats fed a vitamin B6-deficient diet for 4 and 9 weeks. In normal rats, radioactivity was observed in the entire kidney area at 30 min after the injection and at 90 min there was radioactivity only in the papilla, where radioactivity appeared in the parenchyma, mamely the epithelial cells of collecting ducts and the surrounding interstitial tissue. In hyperoxaluric rats, microautoradiograms showed the spotted deposits of 14C-oxalate in both renal papilla and medulla. In 600 x magnification of the autoradiograms, most of the deposits were detected in the epithelial cells of collecting ducts and the surrounding interstitial tissue. These deposits were identified by a polarizing microscope and X-ray microanalysis as crystal deposits of calcium oxalate. These results indicated that oxalate remained for an extended period of time in the epithelial cells of collecting ducts and in the surrounding interstitial tissue in renal papilla, and the calcium oxalate crystals fixed to the same tissue was the first step in the development of calcium oxalate stones.