L-型钙通道电流在D型钠尿肽抑制豚鼠胃动力中的作用

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 4-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-dependent 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 currents via pGC-cGMP-PKG-dependent signal pathway in gastric antral myocytes of guinea pigs.%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,10 nmol/L DNP对IBa的影响.结果 1、10、100 nmol/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、100 nmol/L DNP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,10 nmol/L DNP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10 nmol/L DNP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,10 nmol/L DNP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.