Thus, a role for apical TRPA1 channels has been proposed in the mediation of prostaglandin signalling leading to anion secretion. However, TRP channels are not only expressed by enteric neurons or sensory cells, but also by cells of the transporting epithelium. 8 On the other hand, the interaction of cinnamaldehyde with the same channel triggers motility and secretion enhancing the digestive response while simultaneously contributing to the enjoyment of food. Thus, the stimulation of TRPA1 expressed by neuronal fibres of the enteric nervous system is thought to play a role in inflammatory responses with secretion of signalling molecules associated with hypersensitivity and pain as in inflammatory bowel disease. 1, 2, 6, 7 In the gastrointestinal tract, stimuli generally activate channels on submucosal neurons, leading to influx of Ca 2+ with initiation of signalling cascades that lead both to central sensory perception or local responses. 4 Furthermore, the channels are modulated by a plethora of chemical stimuli including fragrant mono- and diterpenes found naturally in plants, 5 by hormones, by pH or osmolarity. Importantly, certain members of the family can be gated by heat (eg TRPV1 or TRPV3) or cold (TRPA1 or TRPM8). 1, 2 Perhaps owing to the fact that the first member of the family to be discovered is central to phototransduction in drosophila flies, 3 the major focus of attention has so far mostly been on the role of these proteins as molecular sensors for various stimuli. Transient receptor potential (TRP) channels are expressed throughout the gastrointestinal tract where they play multiple roles that are incompletely understood. Pharmacological regulation may be possible. We propose that TRP channels contribute to the intestinal transport of ammonium, with TRPV3 and TRPV4 promising candidate proteins. Application of mucosal NH 4Cl led to dose-dependent and divalent-sensitive increases in G t and I sc, with effects highest in the caecum and colon.
In symmetrical NaCl Ringer, removal of mucosal Ca 2+ and Mg 2+ increased colonic short circuit current (I sc) and conductance (G t) by 0.18 ± 0.06 µeq Immunohistochemically, an apical expression of TRPV3 and TRPV4 could be detected in all tissues, with effects of 2-APB and GSK106790A supporting functional expression. TRPV3 mRNA was only found in the mucosa of the caecum and colon, organs in which NH 4 + was highest (>7 mmol TRPV4 was ubiquitously expressed by mucosal and muscular layers. TRPV2 was highest in the jejunum but almost non-detectable in the colon. TRPM6 was highest in jejunum and colon, with expression of TRPM7 ubiquitous. QPCR data show high duodenal expression of TRPV6. Methodsĭigesta, mucosa and muscular samples from stomach, duodenum, jejunum, ileum, caecum and colon of pigs were analysed via colourimetry, qPCR, Western blot, immunohistochemistry and Ussing chambers.
#Igor pro 6.34 Patch#
Since patch clamp data show that certain members of the transient receptor potential (TRP) family are permeable to NH 4 +, participation in ammonium efflux was investigated. Absorption of ammonia from the gut has consequences that range from encephalitis in hepatic disease to global climate change induced by nitrogenous excretions from livestock.
0 kommentar(er)
