Laboratory of Veterinary Pharmacology, Graduate School of Life and Environmental Science, Osaka Prefecture University, Rinku-Ourai Kita, Izumisano-shi 598-8531, Japan.
J Pharmacol Sci. 2010;112(2):231-41. doi: 10.1254/jphs.09242fp. Epub 2010 Jan 30.
The present study was designed to identify the inhibitory neurotransmitters mediating nonadrenergic noncholinergic relaxation in the longitudinal muscle of C57/BL mouse distal colon. Relaxation induced by electrical field stimulation (EFS) was recorded isotonically in the presence of atropine and guanethidine. Cyclic guanosine-3',5'-monophosphate (cyclic GMP) content was measured by radioimmunoassay. EFS-induced relaxation was inhibited by nitro-L-arginine (L-NNA) and Sn (IV) protoporphyrin dichloride IX (SnPP-IX), a nitric oxide (NO) and carbon monoxide (CO) synthase inhibitor, respectively. A combination of both inhibitors produced an additive effect. ODQ, a soluble guanylate cyclase inhibitor, inhibited EFS-induced relaxation. NOR-1, a NO donor, and carbon monoxide-releasing molecule-2 (CORM-2), a CO donor, treatment relaxed the distal colon and increased cyclic GMP content. The effects of NOR-1 and CORM-2 were inhibited by ODQ. KT5823, a cyclic GMP-dependent protein kinase inhibitor, inhibited EFS-induced relaxation. EFS-induced relaxation in the presence of KT5823 was further inhibited by L-NNA, but not by SnPP-IX. In addition, KT5823 inhibited CORM-2-induced relaxation, but not NOR-1-induced relaxation. H89, a cyclic AMP-dependent protein kinase inhibitor, inhibited EFS-induced relaxation, and EFS-induced relaxation in the presence of H89 was further inhibited by L-NNA. These results suggested that NO and CO function as inhibitory neurotransmitters in the longitudinal muscle of C57BL mouse distal colon.
本研究旨在鉴定介导 C57/BL 小鼠远端结肠纵行肌非肾上腺素非胆碱能松弛的抑制性神经递质。在阿托品和胍乙啶存在的情况下，通过电刺激（EFS）记录等张松弛。通过放射免疫测定测量环鸟苷酸 3'，5'-单磷酸（环 GMP）含量。EFS 诱导的松弛分别被一氧化氮合酶（NOS）和一氧化碳合酶抑制剂硝基-L-精氨酸（L-NNA）和 Sn（IV）原卟啉二氯化物 IX（SnPP-IX）抑制。两种抑制剂的组合产生相加作用。可溶性鸟苷酸环化酶抑制剂 ODQ 抑制 EFS 诱导的松弛。NO 供体 NOR-1 和 CO 供体一氧化碳释放分子-2（CORM-2）处理可使远端结肠松弛并增加环 GMP 含量。NOR-1 和 CORM-2 的作用被 ODQ 抑制。环 GMP 依赖性蛋白激酶抑制剂 KT5823 抑制 EFS 诱导的松弛。在 KT5823 存在下，EFS 诱导的松弛进一步被 L-NNA 抑制，但不受 SnPP-IX 抑制。此外，KT5823 抑制 CORM-2 诱导的松弛，但不抑制 NOR-1 诱导的松弛。环 AMP 依赖性蛋白激酶抑制剂 H89 抑制 EFS 诱导的松弛，并且在 H89 存在下 EFS 诱导的松弛进一步被 L-NNA 抑制。这些结果表明，NO 和 CO 在 C57BL 小鼠远端结肠纵行肌中作为抑制性神经递质发挥作用。
