期刊
DIGESTIVE DISEASES AND SCIENCES
卷 64, 期 5, 页码 1171-1181出版社
SPRINGER
DOI: 10.1007/s10620-018-5417-5
关键词
Colon; Smooth muscle; Isovaleric acid; Branched-chain fatty acid; Cyclic AMP; Adenylyl cyclase; Protein kinase A; SQ22536; H-89; Tetrodotoxin; Nitric oxide synthase; L-N-nitroarginine
资金
- National Institute of Diabetes and Kidney Diseases [DK34153, DK28300, DK15564]
BackgroundIsovaleric acid (IVA) is a 5-carbon branched-chain fatty acid present in fermented foods and produced in the colon by bacterial fermentation of leucine. We previously reported that the shorter, straight-chain fatty acids acetate, propionate and butyrate differentially affect colonic motility; however, the effect of branched-chain fatty acids on gut smooth muscle and motility is unknown.AimsTo determine the effect of IVA on contractility of colonic smooth muscle.MethodsMurine colonic segments were placed in a longitudinal orientation in organ baths in Krebs buffer and fastened to force transducers. Segments were contracted with acetylcholine (ACh), and the effects of IVA on ACh-induced contraction were measured in the absence and presence of tetrodotoxin (TTx) or inhibitors of nitric oxide synthase [L-N-nitroarginine (L-NNA)] or adenylate cyclase (SQ22536). The effect of IVA on ACh-induced contraction was also measured in isolated muscle cells in the presence or absence of SQ22536 or protein kinase A (PKA) inhibitor (H-89). Direct activation of PKA was measured in isolated muscle cells.ResultsIn colonic segments, ACh-induced contraction was inhibited by IVA in a concentration-dependent fashion; the IVA response was not affected by TTx or L-NNA but inhibited by SQ22536. Similarly, in isolated colonic muscle cells, ACh-induced contraction was inhibited by IVA in a concentration-dependent fashion and the effect blocked by SQ22536 and H-89. IVA also increased PKA activity in isolated smooth muscle cells.ConclusionsThe branched-chain fatty acid IVA acts directly on colonic smooth muscle and causes muscle relaxation via the PKA pathway.
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