Segmental and Cellular V1a Receptor Distribution in the Mammalian Kidney

Vasopressin (AVP) promotes urinary concentration via its V2 receptors in the distal nephron and collecting duct of the kidney. Parallel activation of V1a receptors (V1aR) has been implicated in renal acid‐base handling, but cell type‐related information on this receptor type is still scarce. We have analyzed segmental and cellular distribution of V1aR in mouse, rat, and human kidneys using new antisera. Localization data were supported by functional studies. An anti‐V1aR was generated and its specificity verified using V1aR‐knockout tissues. Immunofluorescence and super resolution imaging (SIM) were applied for localization studies. AVP‐deficient Brattleboro were analyzed using the V1aR‐specific agonist, AO‐4‐67. The V1aR antibody showed basolateral membrane‐associated and punctate cytoplasmic signal in alpha‐type intercalated cells of connecting tubules and collecting ducts in rodent and human kidneys. In contrast, beta‐type intercalated cells showed only punctate perinuclear and subapical V1aR signal. Double‐labeling of V1aR with markers for flotillin‐1 (lipid rafts), GM130 (trans‐Golgi network protein), Rab9 (endosomal marker), or LAMP1 (lysosomal marker) suggested broad distribution of the receptor in the respective cellular structures in both types of intercalated cells. Administration of AO‐4‐67 to Brattleboro rats for 4h resulted in luminal trafficking of V‐ATPase in alpha‐type intercalated cells, whereas basolateral V‐ATPase or luminal pendrin of beta‐intercalated cells were not affected by the stimulation. In summary, divergent cellular V1aR distribution in alpha‐ vs. beta intercalated cells may explain their distinct responsiveness to the V1aR agonist. These results corroborate and extend data on the role of AVP in renal acid‐based handling.