Effects of butyrate on ruminal Ca transport: evidence for the involvement of apically expressed TRPV3 and TRPV4 channels.

The ruminal epithelium absorbs large quantities of NH and Ca. A role for TRPV3 has emerged, but data on TRPV4 are lacking. Furthermore, short-chain fatty acids (SCFA) stimulate ruminal Ca and NH uptake in vivo and in vitro, but the pathway is unclear.

Beyond Ca signalling: the role of TRPV3 in the transport of NH.

Mutations of TRPV3 lead to severe dermal hyperkeratosis in Olmsted syndrome, but whether the mutants are trafficked to the cell membrane or not is controversial. Even less is known about TRPV3 function in intestinal epithelia, although research on ruminants and pigs suggests an involvement in the uptake of NH. It was the purpose of this study to measure the permeability of the human homologue (hTRPV3) to NH, to localize hTRPV3 in human skin equivalents, and to investigate trafficking of the Olmsted mutant G573S.

The TRPV3 channel of the bovine rumen: localization and functional characterization of a protein relevant for ruminal ammonia transport.

Large quantities of ammonia (NH or NH) are absorbed from the gut, associated with encephalitis in hepatic disease, poor protein efficiency in livestock, and emissions of nitrogenous climate gasses. Identifying the transport mechanisms appears urgent. Recent functional and mRNA data suggest that absorption of ammonia from the forestomach of cattle may involve TRPV3 channels.

A comparative study of ammonia transport across ruminal epithelia from Bos indicus crossbreds versus Bos taurus.

Absorption of ammonia from the rumen of cattle decreases nitrogen availability for fermentational protein synthesis, leading to increased competition of cattle with humans for protein and enhancing the release of toxic nitrogenous compounds into the environment. Given that differences in feeding and breeding might induce differences in ruminal ammonia transport, we compared electrophysiological, histological, and molecular biological characteristics of ruminal epithelia of Bos indicus crossbreds (Sahiwal-Mix, SWM) with those of Bos taurus (Holstein-Friesian, HF). As in HF, the stratified cornified epithelium of SWM expressed claudin 1 and 4.

The bovine TRPV3 as a pathway for the uptake of Na, Ca, and NH.

Absorption of ammonia from the gastrointestinal tract results in problems that range from hepatic encephalopathy in humans to poor nitrogen efficiency of cattle with consequences for the global climate. Previous studies on epithelia and cells from the native ruminal epithelium suggest functional involvement of the bovine homologue of TRPV3 (bTRPV3) in ruminal NH4+ transport. Since the conductance of TRP channels to NH4+ has never been studied, bTRPV3 was overexpressed in HEK-293 cells and investigated using the patch-clamp technique and intracellular calcium imaging.