Transport of acetate and sodium in sheep omasum: mutual but asymmetric interactions
Transport of acetate and sodium in sheep omasum: mutual but asymmetric interactions
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Date
2006
Authors
المعتمد, اسامه
Journal Title
Journal ISSN
Volume Title
Publisher
uofk
Abstract
We have studied the transport of acetate across
the isolated epithelium of sheep omasum; no net transport
was observed (Jms Jsm) under Ussing chamber
conditions. Low mucosal pH (pH 6.4) significantly enhanced
Jms acetate and the transport rates of acetate
increased linearly and significantly (r2=0.99) with the
luminal acetate concentration. The presence of another
short chain fatty acid (propionate) did not affect Jms
acetate significantly. Neither addition of 1 mmol l 1
DIDS to the mucosal side nor HCO3 replacement
caused changes of Jms acetate; this does not support the
assumption of acetate transport via anion exchange.
Addition of 1 mmol l 1 amiloride to the mucosal side
significantly decreased acetate fluxes at high mucosal
acetate concentration (100 mmol l 1) and low pH (6.4)
indicating interaction between acetate uptake in the
undissociated form, intracellular release of protons and
activation of Na+/H+ exchange (NHE). However, the
mutual interaction between Na transport via NHE and
acetate transport is asymmetric. Stimulation or inhibition
of Na transport via NHE is much more pronounced
than the corresponding changes of acetate fluxes. Thus,
the obtained results support the conclusion that acetate
is transported via simple diffusion and probably predominantly
in the protonated form, thereby explaining
the positive and mutual interaction between Na transport
and short chain fatty acids
Description
This paper had been presented for promotion at the university of Khartoum. To get the full text please contact the other at osama elmotamed
Keywords
Omasum Æ Sheep Æ SCFA Æ Transport NHE