中文摘要：

目的探讨L-型钙通道电流在D型钠尿肽（DNP）抑制豚鼠胃动力中的作用及机制。方法制作豚鼠胃窦部环形肌肌条后，用多道生理记录仪记录环形肌自发性收缩活动；分离环形肌细胞后，用膜片钳记录细胞L-型钡电流（IBa），以IBa代表钙电流；观察不同抑制剂预处理后，10nmol／LDNP对IBa的影响。结果1、10、100nmol／LDNP抑制豚鼠胃窦环形肌自发性收缩的幅度分别为（35．00±7．00）％、（54．00±8．00）％、（78．00±13．00）％，呈明显的剂量依赖性（r=0．923，P〈0．05）。1、10、100nmol／LDNP抑制豚鼠胃窦环形肌细胞上IBa分别为（60．12±2．02）％、（57．12±3．02）％、（42．12±3．16）％。用鸟苷酸环化酶抑制剂LY83583预处理后，10nmoL／LDNP对IBa的抑制作用由预处理前的（67．12±4．02）％减弱为（88．03±4．15）％；用cGMP依赖的蛋白激酶G抑制剂KT5823预处理后，几乎完全阻断了10nmol／LDNP引起的IBa抑制作用；而用cGMP敏感的磷酸酯酶抑制剂zaparinast预处理后，10nmol／LDNP对IBa的抑制作用由预处理前的（67．12±4．02）％增强至（53．00±4．23）％。结论DNP能明显抑制豚鼠胃窦环形肌自发性收缩，其作用机制可能与pGC—cGMP—PKG通路有关。

英文摘要：

Objective To investigate the role of L-type calcium current in DNP-induced inhibition of gastric motility and its mechanism in gastric antral myocytes of guinea pigs. Methods The spontaneous contraction of gastric antral circular muscles of guinea pigs was recorded by a d-channel physiograph. The whole-cell patch-clamp technique was used to record IBa as L-type calcium channel currents. Results DNP inhibited spontaneous contraction and exhibited a dose-de- pendent manner at the concentrations of 1 nmol/L, 10 nmol/L and 100 nmol/L, DNP inhibited spontaneous contraction （ 35.00 ± 7.00） % , （54.00 ± 8.00 ） %, （ 78.00 ± 13.00 ） % ; DNP suppressed IBa in a dose-dependant manner at the concentrations of 1 nmol/L, 10 nmol/L and 100 nmol/L,DNP inhibited IBa to （60.12 ± 2.02）%, （57.12 ± 3.02）%, and （42.12 ± 3.16）%, respectively in gastric antral circular smooth muscle cells （SMCs） of guinea pigs. DNP-induced inhibition of IBa was partially blocked by LY83583, an inhibitor of guanylate cyclase, the inhibited amplitude from （67.12 ±4.02） % to （88.03 ± 4.15 ） %. KT5823, a cGMP-dependent protein kinase （PKG） inhibitor, almost completely blocked DNP-induced inhibition of IBa. However, DNP-induced inhibition of IBa was potentiated by zaprinast, an inhibitor of cGMP-sensitive phosphodiesterase, the inhibited amplitude from （67.12 ±4.02） % to （53.00 ±4.23 ） %. Conclusions DNP significantly inhibits gastric motility in the gastric antrum of guinea pigs. DNP inhibits L-type calcium channel curents via pGC-cGMP-PKG-dependent signal pathway in gastric antral myocytes of guinea pigs.