Refulation of PAF biosynthesis and its role in salivary secretion

血小板活化因子(PAP)是由多种炎症和免疫相关细胞释放出来的。此外，PAF的产生在更广泛的细胞和组织中得到了证实，这表明PAF具有多种生理和病理作用。我们之前已经证明，PAF是在狗的唾液腺细胞受到生理刺激时产生的。1.乙酰胆碱(ACh)、苯丙氨酸、异丙肾上腺素和8BR-环磷酸腺苷增加Lyso-PAP：乙酰辅酶A乙酰转移酶(ACT)和DDT-不敏感胆碱磷酸转移酶。ACh和苯肾上腺素以钙依赖的方式增加ACT和PAP的生成。2用RT-PCR技术检测唾液腺PAF受体基因的表达，研究唾液腺PAP受体的表达。从豚鼠唾液腺中检测到PAP受体特异性聚合酶链式反应片段，但不能从狗唾液腺中检测到特异性扩增。3 X…对更多注射了豚鼠和狗颌下腺mRNA的非洲斑羚卵母细胞进行了电生理分析。1um PAP可使注射豚鼠颌下腺基因的卵母细胞产生一条小电流，但不能引起犬颌下腺的电流。4PAP可促进豚鼠颌下腺切片中粘蛋白的释放。为评价其细胞内活性，检测了PAP对膜部分Na^，K^-ATPase活性的影响。PAF对犬颌下腺细胞膜的Na~+，K~+-ATPase有抑制作用。PAP受体拮抗剂BN-50739可拮抗低浓度PAP的抑制作用，但不能拮抗高浓度PAP的抑制作用。动力学分析表明，PAP对Na，K~+-ATPase的抑制作用不是由于PAP与酶上K~+或Na~+结合部位的竞争，而是通过复杂的抑制机制。这一结果提示：L：PAP的生物合成是通过重塑途径调节自主神经的；2：PAP受体在豚鼠唾液腺中表达，具有刺激分泌反应的功能；3：PAP可能作为细胞内的信号信使调节唾液腺的分泌反应。较少

Platelet-Activating Factor (PAP) was released from a variety of inflammatory and immune-related cells. Moreover, PAF production has been demonstrated in a wider variety of cells and tissues, and suggested that PAF plays various physiological and pathological roles. We have previously shown that PAF is generated upon physiological stimulations in dog salivary gland cells. The present study examined the regulation of PAP biosynthesis and its role in secretory response in salivary glands.1 Acetylcholine (ACh), phenyleprine, isoproterenol and 8Br-cyclic AMP increased lyso-PAP : acetylCoA acetyltransferase (ACT) and DDT-insensiteve cholinephosphotransferase. ACh and phenylephrine increased ACT, and PAP generation in a Ca^2^+-dependent manner.2 PAP receptor expression in salivary glands was studied by examining PAF receptor gene expression using the RT-PCR technique. The specific amplification of PAP receptor-specific PCR fragment from guinea pig, but not dog salivary glands was detected.3 X … More enopus laevis oocytes injected with mRNA from submandibular glands of guinea pig and dogs were electrohysiologically analysed. Application of 1 muM PAP elicited a small current in the oocytes injected with mRNA from guinea pig but not dog submandibular glands.4 PAP stimulated mucin release in the slice of gunea pig submandibular glands.5 PAP is not releasable out of the cells but retained intracellulary in the cells. To assess its intracellular activity, the effect of PAP on Na^+, K^+-ATPase activity in the membrane fraction was examined. PAF inhibited Na^+, K^+-ATPase in the membrane preparations of dog submandibular glands. The inhibitory effect of a low concentration but not of high concentrations of PAP was antagonized by a PAP-receptor antagonists, BN 50739. Kinetic analysis of PAP-induced inhibition of Na^+, K^+-ATPase suggests that the inhibition of Na^+, K^+-ATPase by PAP is not due to competition by PAP at K^+-or Na^+-binding sites on the enzyme, but by complex inhibitory mechanisms.These results suggested that l : PAP biosynthesis is regulated autonomic nerve via remodelling pathway, 2 : PAP receptor is expressed guinea pig salivary gland and functions to stimulate secretory response, 3 : PAP may act as intracellular signal messenger to modulate secretory response in salivary glands. Less