The role of sympathetic nervous system in regulation of gastric acid secretion.

1.电刺激乌拉坦麻醉大鼠内脏神经、胃交感神经，减少组胺刺激的胃酸分泌和粘膜血流量(MBF)。这种对酸分泌和MBF的抑制可被α受体阻滞剂酚妥拉明取消，但不能被β受体阻滞剂普萘洛尔取消。在乌拉坦麻醉大鼠，注入胆碱能M受体激动剂Bethan ecol或五肽胃泌素，并未观察到组胺及其代谢产物1-甲基组胺向胃液和门静脉释放的增加。此外，在体外胃粘膜灌流实验中，这些药物也不能增加组胺及其代谢物的释放。此前，我们通过α-1肾上腺素受体介导的机制，表明电刺激内脏神经减少了BEO和五胃泌素诱导的胃酸分泌，而不减少MBF。另一方面，在本研究中，刺激内脏神经对组胺诱导的胃酸分泌的抑制作用次于MBF的减少。因此，位于含有组胺的细胞上的α-1肾上腺素受体减少组胺释放的可能性被提出。但是，在目前的实验中，苯二酚或五肽胃泌素不能促进组胺的释放。这些结果表明，α-1肾上腺素受体位于壁细胞上，从而减少了苯二酚和五胃泌素诱导的大鼠的胃酸分泌。

1. In the urethane-anesthetized rats, electrical stimulation of the splanchnic nerve, gastric sympathetic nerve, reduced histamine-stimulated gastric acid secretion and mucosal blood flow (MBF). This inhibition of acid secretion and MBF was abolished by phentolamine, an alpha-adrenoceptor blocking agent, but not by propranolol, a beta-adrenoceptor blocking agent.2. In urethane-anesthetized rats, increased release of histamine and 1-methyl histamine, a metabolite of histamine, into gastric juice and portal vein was not observed during infusion of bethanechol, a cholinergic muscarinic receptor agonist, or pentagastrin. Furthermore, in in vitro experiment with perfusion of gastric mucosa, these agents also could not increase the release of histamine and its metabolite.Previously, we showed that electrical stimulation of the splanchnic nerve reduced the bethanechol- and pentagastrin-induced gastric acid secretion without reduction of MBF, through alpha-1 adrenoceptor-mediated mechanisms. On the other hand, inhibition of histamine-induced acid secretion by stimulation of the splanchnic nerve, in the present study, was secondary to a reduction of MBF. Thus, a possibility that alpha-1 adrenoceptors located on the histamine-containing cells reduce the release of histamine was raised. But, in the present experiment, the release of histamine was not enhanced by bethanechol or pentagastrin. From these results, it is suggested that alpha-1 adrenoceptors locate on parietal cells, thereby reducing bethanechol- and pentagastrin-induced acid secretion in rats.