钾通道在D型钠尿肽抑制胃动力中的作用

目的:探讨钾通道在D型钠尿肽抑制豚鼠胃窦环形肌自发性收缩活动中的作用.方法:采用四道生理记录仪记录豚鼠胃窦环形肌自发性收缩活动;应用放射免疫法测定豚鼠胃窦环形肌组织和灌流液中环-磷酸鸟苷(cGMP)含量;运用全细胞模式的膜片钳技术记录豚鼠胃窦环形肌上钙敏感钾电流和延迟整流型钾电流.结果:DNP抑制豚鼠胃窦环形肌自发性收缩活动并呈现剂量依赖性.1、10、100及1000nmol/L的DNP抑制自发性收缩幅度分别为35%±6%、54%±6%、78%±13%及94%±6%.10 nmol/L鸟苷酸环化酶抑制剂LY83583使收缩幅度抑制减弱(42%±6%vs60%±4%.P<0.05);而用100 nm01/L的cGMP依赖的磷酸脂酶抑制剂zaparinast使DNP对胃窦环行肌自发性收缩的抑制效应增强(72%±7%vs58%±5%,P<0.05).DNP明显增加豚鼠胃窦环形肌组织和灌流液中的cGMP水平.10 nmol/LDNP增加豚鼠胃窦环形肌上钙敏感钾电流,在60mV时增加的幅值为62.31%±3.22%,抑制延迟整流型钾电流,在60 mV时抑制幅度为18%±2.3%.结论:DNP通过增加I<,K(ca)>和cGMP途径实现对豚鼠胃窦环形肌的舒张作用.I<,K(v)>不参与此过程,但在维持豚鼠胃窦环形肌细胞的静息膜电位中起重要作用.

Role of potassium channels in Dendroaspis natriuretic peptide-induced inhibition of gastric motility

AIM:To investigate the role of potassium channels in Dendroaspis natriuretic peptide(DNP)-induced relaxation of gastric antral circular smooth muscle of guinea pigs.METHODS:The spontaneous contraction of gastric antral circular muscle of guinea pigs was recorded using a four-channel physiograph.The contents of cyclic guanosine monophosphate(cGMP) in gastric antral smooth muscle tissue and in perfusion medium were measured by radioimmunoassay.The whole cell patch-clamp technique was used to record calcium-ac...