Histocytochemical study of Spot 35-calbindin-D28K and Ca2+-ATPase in rat kidney |
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| Authors: | Junichiro J KAZAMA Tetsuro TAKEDA Takashi KATAGIRI Ryozo KUWANO Toshiro KUMANISHI Hidehiro OZAWA Masaaki ARAKAWA |
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| Affiliation: | Department of Medicine (II), Department of Neuropathology, Niigata, Japan;Department of Oral Anatomy (I), Niigata, Japan;Research Laboratory for Molecular Genetics, Niigata, Japan;Niigata University, Niigata, Japan |
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| Abstract: | Summary: We determined the distribution of Spot 35-calbindin-D28K, a vitamin-D dependent calciumbinding protein, in rat kidney using histochemical methods and compared it with the distribution of Ca2+-ATPase activity. Spot 35-calbindin-D28K immunoreactivity was localized in the cytosol of urinary epithelial cells in distal convoluted tubules (DCT), connecting tubules (CNT) and cortical collecting ducts (CCD), identifying the physiologically confirmed site of active transcellular calcium transport. In the cytosol, the immunoreactivity was clustered near the luminal plasma membrane and around the mitochondria. These findings indicated that Spot 35-calbindin-D28K seemed to have a cytosolic calcium buffering effect in the urinary tubular epithelial cells. Enzyme histochemical analysis showed that Ca2+-ATPase activity was localized at the basolateral plasma membrane of distal nephron segments and was strongest at the cortical thick ascending limb of Henle (CTAL), including the macula densa portion. Ca2+-ATPase activity was not evident in DCT, CNT or CCD. Strong Ca2+-ATPase activity and Spot 35-calbindin-D28K immunoreactivity did not coexist in a urinary tubular cell. |
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| Keywords: | active calcium transport Ca2+-ATPase enzyme histochemistry immunohistochemistry Spot 35-calbindin-D28K |
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