Ultrastructural Characterization of Pannexin 1 Expression Along the Rat Nephron.

Pannexins are transmembrane glycoproteins that share structural and functional similarities with the gap junction proteins innexins and connexins. They play a critical role in paracrine and intracellular signalling, including purinergic signalling via the release of extracellular ATP. The role of pannexins in renal function and the pathophysiology of renal diseases is being intensely studied. However, there are no data on the subcellular localization of pannexin 1 expression in the rat kidney. We studied the distribution of pannexin 1 in the rat kidney, combining light microscopy with immunofluorescent immunohistochemistry and transmission electron microscopy with immunogold pannexin labelling. We found strong expression of pannexin in glomerular podocytes, proximal tubules and collecting ducts; moderate expression in the endothelium of glomerular and peritubular capillaries; thin descending and thick ascending limbs of the loop of Henle; and weaker pannexin 1 expression in the distal tubular epithelium. We described the detailed ultrastructural localization of pannexin 1 expression. This is the first study describing the ultrastructural distribution of pannexin 1 in the rat kidney, one of the most used preclinical models in renal physiology and pathology research. These results provide previously missing data on the precise distribution of pannexin 1 in the rat kidney, which is a prerequisite for a proper understanding of its role in renal physiology and pathophysiology.