Tachykinins in regulation of gastric motility and secretion

The tachykinins constitute a family of neuropeptides with a common C-terminal amino acid sequence. The best known tachykinin is substance P. Tachykinins are found in the nerve plexuses and nerve fibers in the stomach of all species examined. The circular muscle layer is densely innervated, whereas the longitudinal layer and the mucosa are less intensively innervated. Tachykinins are also found in a significant number of afferent neurons with cell bodies in the dorsal root ganglia. Release of tachykinin can be demonstrated in response to both electrical stimulation of the vagus nerves and application of capsaicin. In the stomach all three known tachykinin receptors seem to be present. Although species variations exist, NK-2 receptors are generally present on the musculature, NK-1 receptors on both neurons and muscles, and NK-3 receptors on neurons only. Tachykinins stimulate motility in all parts of the stomach, but tachykinins also appear to inhibit motility in certain situations. Also, motility initiated centrally, mediated through the vagus nerves, is influenced by tachykinins. The precise role of tachykinin in the various motor programs in the stomach is not clear. Gastric acid secretion is influenced by tachykinins in several species. Tachykinins do not seem to act as neurotransmitters directly on parietal cells, but may have a modulatory function. The importance of tachykinins for the regulation of pepsinogen and hormone secretion from the stomach remains unclear. Received 24 August 1999; received after revision 1 December 1999; accepted 3 December 1999     

天然结晶辣椒碱的分析测定

从辣椒果实中分离到一种白色结晶，根据理化性质和质谱，紫外光谱，红外光谱以及高压液相色谱的测定结果，推定该结晶是辣椒碱和二氢辣椒碱的混合物。     

辣椒及其制品中辣味素含量测定法

辣椒中的辣味素由14种酰胺类化合物组成,每种化合物分子中均含有一个氮原子,根据含氮量的多少,通过辣椒素换算系数,可以计算出辣味素的总含量。