In:
Pflügers Archiv - European Journal of Physiology, Springer Science and Business Media LLC, Vol. 474, No. 3 ( 2022-03), p. 315-342
Abstract:
The ruminal epithelium absorbs large quantities of NH 4 + and Ca 2+ . A role for TRPV3 has emerged, but data on TRPV4 are lacking. Furthermore, short-chain fatty acids (SCFA) stimulate ruminal Ca 2+ and NH 4 + uptake in vivo and in vitro, but the pathway is unclear. Sequencing of the bovine homologue (bTRPV4) revealed 96.79% homology to human TRPV4. Two commercial antibodies were tested using HEK-293 cells overexpressing bTRPV4, which in ruminal protein detected a weak band at the expected ~ 100 kDa and several bands ≤ 60 kDa. Immunofluorescence imaging revealed staining of the apical membrane of the stratum granulosum for bTRPV3 and bTRPV4, with cytosolic staining in other layers of the ruminal epithelium. A similar expression pattern was observed in a multilayered ruminal cell culture which developed resistances of 〉 700 Ω · cm 2 with expression of zonula occludens-1 and claudin-4. In Ussing chambers, 2-APB and the TRPV4 agonist GSK1016790A stimulated the short-circuit current across native bovine ruminal epithelia. In whole-cell patch-clamp recordings on HEK-293 cells, bTRPV4 was shown to be permeable to NH 4 + , K + , and Na + and highly sensitive to GSK1016790A, while effects of butyrate − were insignificant. Conversely, bTRPV3 was strongly stimulated by 2-APB and by butyrate − (pH 6.4 〉 pH 7.4), but not by GSK1016790A. Fluorescence calcium imaging experiments suggest that butyrate − stimulates both bTRPV3 and bTRPV4. While expression of bTRPV4 appears to be weaker, both channels are candidates for the ruminal transport of NH 4 + and Ca 2+ . Stimulation by SCFA may involve cytosolic acidification (bTRPV3) and cell swelling (bTRPV4).
Type of Medium:
Online Resource
ISSN:
0031-6768
,
1432-2013
DOI:
10.1007/s00424-021-02647-7
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2022
detail.hit.zdb_id:
1463014-X
SSG:
12
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