STUDY OF PACE-MAKER ACTIVITY IN INTESTINAL SMOOTH-MUSCLE
STUDY OF PACE-MAKER ACTIVITY IN INTESTINAL SMOOTH-MUSCLE
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DOI：
10.1113/jphysiol.1974.sp010629
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发表时间：
1974-01-01
影响因子：
5.5
通讯作者：
WEEMS, WA
中科院分区：
文献类型：
--
作者：
CONNOR, JA;PROSSER, CL;WEEMS, WA
1.在双蔗糖间隙记录猫小肠纵行肌的电活动。2.大约20%的制剂表现出缓慢的，自发的膜电压波动，慢波。这种活动，虽然在一个给定的准备相当均匀，表现出相当大的准备间的变化，振幅，频率和波形。3.应用稳定的超极化电流使慢波频率降低，慢波振幅增加，而去极化电流使频率增加，振幅降低。4.一些没有自发慢波活动的制剂开发慢波时，膜被超极化到一个给定的范围内，这取决于准备，从10到40 mV的大小变化。在某些制剂中，膜从超极化水平的阶跃或斜坡去极化触发慢波。5.当慢波产生制剂的膜电位被钳位在静息电位时，观察到自发的内向电流瞬变。6.在慢波过程中，没有观察到膜电导的变化。7.通过将在电压钳下测量的膜电流应用于在电流钳下独立测量的被动膜电阻和电容，模拟各个制剂的慢波图案。8.除了定义的慢波活动，有时观察到膜电位的电压依赖性振荡。9.应用10-5 M哇巴因不可逆地阻断慢波，并产生等于或略大于慢波峰的膜去极化。复极化的膜的静息电位，或超极化，未能恢复慢波活动。10.去除外部钾产生了可逆的事件序列几乎相同的哇巴因应用程序。11.用蔗糖替代50%的外部氯化钠，慢波活动的上升或下降速率、最大振幅或频率没有变化。蔗糖替代所有外部氯化钠消除慢波5分钟后，然而，活动可以恢复轻微的超极化。长时间暴露于改性浴废除活动。12.在条件性暴露于无钾Krebs溶液后，再输注正常浓度的钾可产生20·5 mV的平均超极化，在自发性制备中可引起活动停滞。13.通过电压钳测量负载钠的非自发活性制剂中的泵电流，并观察到其具有电压依赖性。14.本研究结果表明，猫十二指肠纵行肌中存在一个生电泵，泵电流水平的振荡产生慢波。
1. Electrical activity of longitudinal muscle from cat intestine was recorded in the double sucrose gap. 2. Approximately 20% of the preparations demonstrated slow, spontaneous fluctuations of membrane voltage, slow waves. This activity, although quite uniform in a given preparation, showed considerable inter-preparation variation with respect to amplitude, frequency and wave form. 3. Application of steady hyperpolarizing current decreased slow-wave frequency and increased slow-wave amplitude while depolarizing currents increased frequency and decreased amplitude. 4. Some preparations with no spontaneous slow-wave activity developed slow waves when the membrane was hyperpolarized into a given range which, depending on the preparation, varied in size from 10 to 40 mV. Step or ramp depolarization of the membrane from hyperpolarized levels triggered slow waves in some preparations. 5. When the membrane potential of a slow-wave generating preparation was clamped at the resting potential, spontaneous inward-directed current transients were observed. 6. No changes in membrane conductance were observed during the course of a slow wave. 7. The slow-wave pattern was simulated for individual preparations by applying the membrane current measured under voltage clamp to the passive membrane resistance and capacitance measured independently under current clamp. 8. In addition to the defined slow-wave activity, voltage-dependent oscillations in membrane potential were sometimes observed. 9. Application of 10-5 M ouabain irreversibly blocked slow waves and produced a membrane depolarization equal to or slightly greater than the slow wave crest. Repolarization of the membrane to the resting potential, or hyperpolarization, failed to restore slow-wave activity. 10. Removal of external potassium produced a reversible sequence of events almost identical to those following ouabain application. 11. Replacement of 50% of the external sodium chloride with sucrose produced no changes in slow-wave activity with respect to rates of rise or fall, maximum amplitude or frequency. Sucrose replacement of all external sodium chloride eliminated slow waves after 5 min; however, activity could be restored by a slight hyperpolarization. Longer exposures to the modified bath abolished activity. 12. Following a conditioning exposure to potassium-free Krebs solution, readmission of potassium at normal concentration produced a mean hyperpolarization of 20·5 mV and in spontaneous preparations an arrest of activity. 13. Pump current in sodium-loaded, non-spontaneously active preparations was measured by voltage clamp and was observed to be voltage-dependent. 14. The results of this study indicate that an electrogenic pump is present in longitudinal muscle of cat duodenum, and that oscillations in the level of pump current produce slow waves.