Exintaris B, Lang R J
Department of Physiology, Monash University, Clayton, Victoria 3168, Australia.
Urol Res. 1999 Oct;27(5):328-35. doi: 10.1007/s002400050159.
The effects of intrinsic nerve stimulation on the spontaneous electrical activity of the smooth muscle cells of the guinea pig ureter still attached to its renal pelvis were investigated using standard intracellular microelectrode techniques. Action potentials discharged spontaneously at a frequency of 3.3 +/- 0.2 min(-1) (n = 67) and consisted of an initial rapidly rising spike, followed by a variable period (0.2-5 s) of membrane potential oscillation and a quiescent plateau phase which was terminated by an abrupt repolarisation and after-hyperpolarisation to -66 mV. Transmural electrical stimulation (20-50 Hz for 2 s) transiently decreased the frequency of action potential discharge; the half-amplitude duration of the following action potentials, however, was transiently increased to 156 +/- 12% of control. Substance P (1 microM applied for 2 min) or neurokinin A (100 nM for 2 min) transiently increased the frequency of action potential discharge to 155 +/- 19% and 142 +/- 21%, respectively, of control. The excitatory actions of nerve stimulation or agonist application were reduced by the tachykinin antagonist, MEN 10,627 (1-3 microM), while the inhibitory actions of nerve stimulation were enhanced by MEN 10,627 (1 microM) or thiorphan (1 microM). Capsaicin (10 microM for 10-15 min) also evoked a transient increase in the frequency and half-amplitude duration of the ureteric action potentials, in a manner blocked by MEN 10,627 (3 microM), which was followed by a long period of membrane potential quiescence. Human calcitonin gene related peptide (hCGRP) (100 nM applied for 2-5 min) induced a time-dependent decrease in the frequency amplitude and duration of the spontaneous action potentials, in a manner blocked by glibenclamide (1 microM). It was concluded that the nerve-evoked excitatory and inhibitory changes in the parameters of the spontaneous ureteric action potentials arise from the release of the sensory neuropeptides, tachykinins and CGRP, respectively.
采用标准的细胞内微电极技术，研究了内在神经刺激对豚鼠仍与肾盂相连的输尿管平滑肌细胞自发电活动的影响。动作电位以3.3±0.2次/分钟（n = 67）的频率自发发放，由一个初始快速上升的峰电位组成，随后是膜电位振荡的可变时期（0.2 - 5秒）以及一个静止的平台期，该平台期由突然的复极化和超极化后电位至-66 mV终止。跨膜电刺激（20 - 50 Hz，持续2秒）短暂降低动作电位发放频率；然而，随后动作电位的半幅值持续时间短暂增加至对照的156±12%。P物质（1 μM，施加2分钟）或神经激肽A（100 nM，施加2分钟）分别将动作电位发放频率短暂增加至对照的155±19%和142±21%。速激肽拮抗剂MEN 10,627（1 - 3 μM）可降低神经刺激或激动剂应用的兴奋作用，而MEN 10,627（1 μM）或硫氧还蛋白（1 μM）可增强神经刺激的抑制作用。辣椒素（10 μM，施加10 - 15分钟）也以一种被MEN 10,627（3 μM）阻断的方式，引起输尿管动作电位频率和半幅值持续时间的短暂增加，随后是长时间的膜电位静止。人降钙素基因相关肽（hCGRP）（100 nM，施加2 - 5分钟）以一种被格列本脲（1 μM）阻断的方式，诱导自发动作电位的频率、幅度和持续时间随时间下降。得出的结论是，神经诱发的输尿管自发动作电位参数的兴奋和抑制变化分别源于感觉神经肽、速激肽和CGRP的释放。
