Arpapat Sangpasit; Manutchanok Khamlue; Apussara Watthanakitphibun; Suthankamon Khrongyut; Yada Polsan; Sawetree Pakkarato; Surang Chomphoo; Hisatake Kondo & Wiphawi Hipkaeo

To establish the basis for understanding the functional significance of phospholipase D (PLD)-mediated signaling in the kidney, the localization of PLD2 was examined in adult rat kidneys. In immunolight microscopy, PLD2-immunoreactivity was weak and diffuse across most intrarenal structures, but was notably stronger in the epithelial cells of collecting ducts, suggesting that the involvement of PLD is higher than in the other tubules. In proximal tubules, distinct immunoreactivity appeared in a wavy line-pattern along the luminal surface. In immunoelectron microscopy, immunogold particles were widely distributed throughout the cytoplasm in collecting ducts. They were deposited on plasma membranes, more frequently on apical membranes, and were also in association with vesicles of varying sizes and in the regions lacking obvious membranous structures. In proximal tubule cells, although immunogold particles were observed in distribution similar to but sparser than in collecting ducts, they were largely absent from apical endosomal vesicle zones and microvilli. Moreover, gold particles were deposited on luminal blebs and within flocculent materials covering the tip of apical microvilli. These materials corresponded to the linear adluminal entities showing distinct immunoreactivity in immunolight microscopy. It is likely that these immunoreactive structures were misinterpreted as PLD2-immunoreactive microvilli in an earlier study by others without ultrastructural confirmation.

KEY WORDS: PLD2; Kidney; Renal tubules; Adluminal substances; Blebs.

SANGPASIT, A.; KHAMLUE, M.; WATTHANAKITPHIBUN, A.; KHRONGYUT, S.; POLSAN, Y.; PAKKARATO, S.; CHOMPHOO, S.; KONDO, H. & HIPKAEO, W. Expression and localization of phospholipase D (PLD) in tubule cells of rat kidney. Int. J. Morphol., 44(4):1285-1295, 2026.