Section-specific expression of acid-base and ammonia transporters in the kidney tubules of the goldfish Carassius auratus and their responses to feeding
| Autor: | Sandra Fehsenfeld, Chris M. Wood |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
030110 physiology
0301 basic medicine Gill Fish Proteins Time Factors Physiology Excretion 03 medical and health sciences Ammonia chemistry.chemical_compound Eating Goldfish medicine Carassius auratus Animals RNA Messenger Acidosis Acid-Base Equilibrium Membrane Transport Proteins Transporter Renal epithelium Biological Transport Renal Elimination Kidney Tubules chemistry Biochemistry Gene Expression Regulation medicine.symptom Kidney tubules |
| Zdroj: | American journal of physiology. Renal physiology. 315(6) |
| ISSN: | 1522-1466 |
| Popis: | In teleost fishes, renal contributions to acid-base and ammonia regulation are often neglected compared with the gills. In goldfish, increased renal acid excretion in response to feeding was indicated by increased urine ammonia and inorganic phosphate concentrations and decreased urine pH. By microdissecting the kidney tubules and performing quantitative real-time PCR and/or immunohistochemistry, we profiled the section-specific expression of glutamate dehydrogenase (GDH), glutamine synthetase (GS), Na+/H+-exchanger 3 (NHE3), carbonic anhydrase II (CAIIa), V-H+-ATPase subunit 1b, Cl−/[Formula: see text]-exchanger 1 (AE1), Na+/[Formula: see text]-cotransporter 1 (NBC1), Na+/K+-ATPase subunit 1α, and Rhesus-proteins Rhbg, Rhcg1a, and Rhcg1b. Here, we show for the first time that 1) the proximal tubule appears to be the major site for ammoniagenesis, 2) epithelial transporters are differentially expressed along the renal tubule, and 3) a potential feeding-related “acidic tide” results in the differential regulation of epithelial transporters, resembling the mammalian renal response to a metabolic acidosis. Specifically, GDH and NHE3 mRNAs were upregulated and GS downregulated in the proximal tubule upon feeding, suggesting this section as a major site for ammoniagenesis and acid secretion. The distal tubule may play a major role in renal ammonia secretion, with feeding-induced upregulation of mRNA and protein for apical NHE3, cytoplasmic CAIIa, universal Rhcg1a and apical Rhcg1b, and downregulation of basolateral Rhbg and AE1. Changes in mRNA expression of the Wolffian ducts and bladder suggest supporting roles in fine-tuning urine composition. The present study verifies an important renal contribution to acid-base balance and emphasizes that studies looking at the whole kidney may overlook key section-specific responses. |
| Databáze: | OpenAIRE |
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