Key result
Endothelin A receptor-like immunoreactivity is predominantly located on the basal infoldings of the distal renal tubules and inner medullary collecting ducts in the rat kidney.
Endothelin A receptors are localized on the basal infoldings of rat distal tubules and inner medullary collecting ducts, suggesting a role in modulating renal tubular function.
May guide ET_A signaling studies in distal nephron; leaves open human renal relevance pending translational data.
We investigated the distribution of endothelin A (ET(A)) receptor-like immunoreactivity in the rat kidney using affinity-purified antibodies against amino acid residues 403-417 of the rat ET(A) receptor modified by the multiple antigen peptide complex system. Western blot analysis using the affinity-purified anti-ET(A) antibody detected bands of approximately 47.3 and 64.5 kDa in the rat kidney. By light microscopy, ET(A) receptor-like immunoreactivity was seen in the basal side of the renal tubules and collecting ducts. The most intense immunoreactivity was present in the distal renal tubules and inner medullary collecting ducts. In addition to the basal infoldings, immunoreactive puncta were scattered in the epithelial cells of the renal tubules and collecting ducts. Specimens prepared using the pre-embedding method were examined by electron microscopy, and some immunopositive signals were seen on the basal infodings of the renal tubules and collecting ducts. The lengths of immunopositive cytoplasmic membrane were far longer in the distal tubules and inner medullary collecting ducts than in the proximal tubules and outer medullary collecting ducts. Immunopositive signals were also sometimes observed in the thick portion of Henle's loop, but never in the thin portion. We have not previously detected immunopositive signals on the renal vascular systems with the antibody used here. These results suggest that endothelin acts on the basal infoldings through the ET(A) receptor, particularly in the distal tubules and inner medullary collecting ducts, although involvement of the ET(B) receptor cannot be excluded.
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Yamamoto et al. (2008) studied Normal anatomy (n=7). Affinity-purified anti-ETA antibody vs. Pre-immune serum or preabsorbed antibody was evaluated on Distribution of ETA receptor-like immunoreactivity. Endothelin A receptor-like immunoreactivity is predominantly located on the basal infoldings of the distal renal tubules and inner medullary collecting ducts in the rat kidney.
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