English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The transmural potential difference of isolated rat duodenum and the membrane potential of its epithelial cell were examined during changes of the ionic medium at both warm (31--35 degrees C) and cold temperatures (2--5 degrees C). In the range of low external K+ concentrations, cooling produced an immediate and reversible depolarization of the membrane potential (around -10 mV) greater than that estimated from a simple thermodynamic temperature effect (RT/F). Such a temperature sensitive component of the membrane potential at 31 degrees C was completely abolished by anoxia and serosal ouabain. Readmission of K+ to the bathing fluid of duodenum previously deprived of K+ and loaded by Na+ caused a remarkable transient hyperpolarization of the epithelial membrane, which was abolished by serosal ouabain. Decreases in the value of transmural potential difference were also produced by cooling, anoxia and serosal ouabain, but these were so small that concurrent changes in the membrane potential could be regarded as chiefly reflecting changes in the effective emf of the cell. Thus, an electrogenic Na+-K+ exchange pump located on the serosal membrane of the duodenal epithelial cells was shown to contribute significantly to the membrane potential under normal conditions (up to around -7 mV). The coupling ratio of Na+-efflux and K+-influx associated with this pump was estimated by the Mullins-Noda equation (1963) to be approximately 4:3 under the physiological steady-state conditions.

Contribution of an Electrogenic Sodium Pump to the Membrane Potential in the Intestinal Epithelial Cell