Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
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Compound
Target Concepts:
Gene/Protein
Disease
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Enzyme
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Query: EC:3.6.1.3 (
ATPase
)
65,361
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Experiments were conducted on adult rainbow trout (Oncorhynchus mykiss) to test the hypothesis that SLC9 Na+/H+ exchangers (
SLC9A2
, NHE2; and SLC9A3, NHE3) on the gill epithelium are localized specifically to a subset of mitochondria-rich cells (MRCs) that are unable to bind peanut lectin agglutinin (PNA). This cell type, termed the PNA- MRC, is a sub-type of MRC believed to function in Na+ uptake and acid excretion. A technique using biotinylated PNA was used to distinguish between the PNA- and PNA+ MRCs on fixed gill sections. In contrast to expectations, both NHE2 (mRNA) and NHE3 (protein) were confined to cells enriched with Na+/K+-
ATPase
and capable of binding PNA. Thus, in trout, NHE2 and NHE3 are localized to PNA+ MRCs, the cells previously believed to be responsible for Cl- uptake and base excretion. Levels of mRNA for NHE2, the predominant isoform in the gill, were increased during 72 h of hypercapnic acidosis; NHE3 mRNA and protein levels were unaffected. Because plasma cortisol levels were increased during hypercapnia (from 35.3+/-9.4 to 100.1+/-30.9 ng ml(-1)), the effects of experimentally elevated cortisol levels on NHE expression were investigated. The elevation of plasma cortisol using intraperitoneal implants caused a significant increase in NHE2 mRNA expression without affecting NHE3 mRNA or protein abundance. Thus, we suggest that NHE2 contributes to acid-base regulation during hypercapnia owing to its transcriptional regulation by cortisol. The finding of NHE expression in PNA+ MRCs is discussed with reference to current models of ionic and acid-base regulation in teleost fish.
...
PMID:Branchial expression and localization of SLC9A2 and SLC9A3 sodium/hydrogen exchangers and their possible role in acid-base regulation in freshwater rainbow trout (Oncorhynchus mykiss). 1862 81
Fermentative organs such as the caecum, the colon, and the rumen have evolved to produce and absorb energy rich short chain fatty acids (SCFA) from otherwise indigestible substrates. Classical models postulate diffusional uptake of the undissociated acid (HSCFA). However, in net terms, a major part of SCFA absorption occurs with uptake of Na
+
and resembles classical, coupled electroneutral NaCl transport. Considerable evidence suggests that the anion transporting proteins expressed by epithelia of fermentative organs are poorly selective and that their main function may be to transport acetate
-
, propionate
-
, butyrate
-
and HCO
3
-
as the physiologically relevant anions. Apical uptake of SCFA thus involves non-saturable diffusion of the undissociated acid (HSCFA), SCFA
-
/HCO
3
-
exchange via DRA (SLC26A3) and/or SCFA
-
-H
+
symport (MCT1, SLC16A1). All mechanisms lead to cytosolic acidification with stimulation of Na
+
/H
+
exchange via NHE (
SLC9A2
/3). Basolaterally, Na
+
leaves via the Na
+
/K
+
-
ATPase
with recirculation of K
+
. Na
+
efflux drives the transport of SCFA
-
anions through volume-regulated anion channels, such as maxi-anion channels (possibly SLCO2A1), LRRC8, anoctamins, or uncoupled exchangers. When luminal buffering is inadequate, basolateral efflux will increasingly involve SCFA
-
/ HCO
3
-
exchange (AE1/2, SCL4A1/2), or efflux of SCFA
-
with H
+
(MCT1/4, SLC16A1/3). Furthermore, protons can be basolaterally removed by NHE1 (SCL9A1) or NBCe1 (SLC4A4). The purpose of these transport proteins is to maximize the amount of SCFA transported from the tightly buffered ingesta while minimizing acid transport through the epithelium. As known from the rumen for many decades, a disturbance of these processes is likely to cause severe colonic disease.
...
PMID:A look at the smelly side of physiology: transport of short chain fatty acids. 2930 50
