Publikationsdatenbank

The bovine rumen expresses bTRPV3 channels as a pathway for the uptake of NH4+ (2018)

Art

Poster

Autoren

Liebe, F (WE 2)

Liebe, H (WE 2)

Vitzthum, C (WE 2)

Käßmeyer, S (WE 1)

Sponder, G (WE 2)

Stumpff, F (WE 2)

Kongress

23. Tagung der DVG-Fachgruppe Physiologie und Biochemie der Deutschen Veterinärmedizinischen Gesellschaft

Wien, 21. – 23.02.2018

Quelle

23. Tagung der Fachgruppe Physiologie und Biochemie der Deutschen Veterinärmedizinischen Gesellschaft : PROGRAMM & ABSTRACTS — Veterinärmedizinische Universität Wien (Hrsg.)

— S. 51

ISBN: 978-3-86345-307-7

Sprache

Englisch

Verweise

URL (Volltext): https://www.vetmeduni.ac.at/fileadmin/v/DVG-Tagung-2018/160218_Abstract_Program_Guide_sortiert_final.pdf

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Emissions of nitrogen by dairy cattle play a considerable role in climate change. These are associated with the degradation of dietary protein into ammonium (NH4 +) that is absorbed across the ruminal epithelium, possibly via bTRPV3 [1]. To confirm permeability of bTRPV3 to NH4 + [2], Xenopus oocytes were either injected with water (control) or strep-tagged bTRPV3-cRNA. In single channel experiments in symmetrical NH4 +, 90% patches from bTRPV3 cells showed single channel events versus 60% of patches from controls. Large channels of 158 ± 12 pS (n = 11) could only be observed in bTRPV3 patches. When corrected for concentration, this conductance was identical to that previously obtained for NH4 + in HEK-293 cells expressing bTRPV3 (p = 0.79) [2]. Conductance to Na+ was 101 ± 10 pS, again reflecting the concentration-corrected value in HEK-293 cells (p = 0.84) [2]. Additional endogenous channels were observed in both groups, but more frequently in control patches (57%; ~32 pS for Na+; ~44 pS for NH4 +) than in bTRPV3 patches (34%; ~36 pS for Na+; ~48 pS for NH4 +). Endogenous channels appeared twice as frequently in patches from Xenopus oocytes versus HEK-293 cells [2]. In oocytes studied with double-barreled pH-sensitive microelectrodes, the relative permeability of Na+ or NH4 + versus NMDG+ was significantly higher in bTRPV3 than in controls (both n = 17, p < 0.02). Interestingly, exposure to NH4Cl led to a significant acidification (p < 0.001) in both bTRPV3 and control oocytes (pHi ~ 6.4). To investigate expression in the bovine rumen, a commercial TRPV3 antibody was used revealing staining of the stratum spinosum and granulosum. The specificity of the antibody was tested using western blotting and immunohistological staining of bTRPV3 and control Xenopus oocytes. In conclusion, we suggest that bTRPV3 participates in the ruminal uptake of NH4 + with expression levels highest in the apical layers of the functional transporting syncytium. Furthermore, we show that the single channel conductance of bTRPV3 is similar after expression in Xenopus oocytes and HEK-293 cells. However, Xenopus oocytes, in particular, also express endogenous NH4 +- permeable channels with a lower single channel conductance.