Modulation of renal CNG-A3 sodium channel in rats subjected to low- and high-sodium diets.
In this work, we studied the mRNA distribution of CNG-A3, an amiloride-sensitive sodium channel that belongs to the cyclic nucleotide-gated (CNG) family of channels, along the rat nephron. The possible involvement of aldosterone in this process was also studied. We also evaluated its expression in rats subjected to diets with different concentrations of sodium or to alterations in aldosterone plasma levels. Total RNA isolated from whole kidney and/or dissected nephron segments of Wistar rats subjected to low- and high-sodium diets, furosemide treatment, adrenalectomy, and adrenalectomy with replacement by aldosterone were analyzed by the use of Western blot, ribonuclease protection assay (RPA) and/or reverse transcription followed by semi-quantitative polymerase chain reaction (RT-PCR). CNG-A3 sodium channel mRNA and protein expression, in whole kidneys of rats subjected to high-Na+ diet, were lower than those in animals given a low-salt diet. Renal CNG-A3 mRNA expression was also decreased in adrenalectomized rats, and was normalized by aldosterone replacement. Moreover, a CNG-A3 mRNA expression study in different nephron segments revealed that aldosterone modulation is present in the cortical thick ascending loop (cTAL) and cortical collecting duct (CCD). This result suggests that CNG-A3 is responsive to the same hormone signaling as the amiloride sensitive sodium channel ENaC and suggests the CNG-A3 may have a physiological role in sodium reabsorption.
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS-Bloco G, CEP 21949-900 Rio de Janeiro, RJ, Brazil.
Horacio J
HJ
Novaira
Bruno F
BF
Botelho
Regina C
RC
Goldenberg
Sandra E
SE
Guggino
Marcelo M
MM
Morales
D000450:Aldosterone / Q000097:blood / Q000502:physiology; D000818:Animals; D054815:Cyclic Nucleotide-Gated Cation Channels; D004039:Diet, Sodium-Restricted; D005786:Gene Expression Regulation / Q000187:drug effects*; D007473:Ion Channels / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D007668:Kidney; D009399:Nephrons / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000032:analysis / Q000235:genetics*; D017673:Sodium Chloride, Dietary / Q000378:metabolism / Q000494:pharmacology*; D014018:Tissue Distribution
C108144:Cnga3 protein, rat; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D012333:RNA, Messenger; D015222:Sodium Channels; D017673:Sodium Chloride, Dietary; D000450:Aldosterone