Three distinct mechanisms of HCO3- secretion in rat distal colon.

@article{VIdyasagar2004ThreeDM,
  title={Three distinct mechanisms of HCO3- secretion in rat distal colon.},
  author={Sadasivan VIdyasagar and Vazhaikkurichi M. Rajendran and Henry J. Binder},
  journal={American journal of physiology. Cell physiology},
  year={2004},
  volume={287 3},
  pages={
          C612-21
        }
}
HCO(3)(-) secretion has long been recognized in the mammalian colon, but it has not been well characterized. Although most studies of colonic HCO(3)(-) secretion have revealed evidence of lumen Cl(-) dependence, suggesting a role for apical membrane Cl(-)/HCO(3)(-) exchange, direct examination of HCO(3)(-) secretion in isolated crypt from rat distal colon did not identify Cl(-)-dependent HCO(3)(-) secretion but did reveal cAMP-induced, Cl(-)-independent HCO(3)(-) secretion. Studies were… 
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TLDR
The results suggest that a NPPB-sensitive, DIDS-resistant Cl(-)/ HCO(3)(-) exchanger is present in the apical membrane, and mediates Cl(-)-dependent H CO(3-) secretion, probably responsible for the formation of the high pH at the mucosal surface.
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It is concluded that HCO(3)(-)- secretion in the ileum follows a mucosal Cl(-)-dependent pathway and a cAMP-activated pathway, each being distinct from each other.
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TLDR
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TLDR
The rat distal colon manifests a segmental discrepancy in anion transport stimulated by luminal forskolin, and HCO(3)(-) might be the main component of the anion secretion in DC(4).
Calcium-sensing receptor stimulates Cl(-)- and SCFA-dependent but inhibits cAMP-dependent HCO3(-) secretion in colon.
TLDR
Results suggest a new paradigm for regulation of intestinal ion transport in which HCO3(-) secretion may be fine-tuned by CaSR in accordance with nutrient availability and state of digestion and absorption.
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TLDR
Recent progress in the regulation of HCO3 secretion in the distal colon is summarized with emphasis on the interrelationship between Cl-dependent, short-chain fatty acid (SCFA)-dependent, and cAMP-induced H CO3 secretion.
Identification of Functionally Distinct Na-HCO3 Co-Transporters in Colon
TLDR
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Secretagogue stimulation enhances NBCe1 (electrogenic Na(+)/HCO(3)(-) cotransporter) surface expression in murine colonic crypts.
TLDR
Results demonstrate a secretagogue-induced increase of NBCe1 membrane expression and suggest vesicle traffic and exocytosis might represent a novel mechanism of intestinal NBC activation by secretagogues.
Aldosterone induces active K⁺ secretion by enhancing mucosal expression of Kcnn4c and Kcnma1 channels in rat distal colon.
TLDR
Observed observations indicate that aldosterone induces active K(+) secretion by enhancing mucosal Kcnn4c and Kcnma1 expression at the transcriptional level, and this was prevented by exposure to actinomycin D (an RNA synthesis inhibitor).
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References

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