Mittal R K, Fisher M, McCallum R W, Rochester D F, Dent J, Sluss J
Department of Internal Medicine, University of Virginia, Charlottesville 22908.
Am J Physiol. 1990 Apr;258(4 Pt 1):G624-30. doi: 10.1152/ajpgi.1990.258.4.G624.
We studied the effects of increased intra-abdominal pressure on the lower esophageal sphincter (LES) pressure in 15 healthy subjects. The role of the diaphragm in the genesis of LES pressure during increased intra-abdominal pressure was determined by measuring diaphragm electromyogram (EMG). The latter was recorded using bipolar intraesophageal platinum electrodes that were placed on the nonpressure sensing surface of the sleeve device. We also measured the LES pressure response to increased intra-abdominal pressure during inhibition of the smooth muscles of the LES by intravenous atropine (12 micrograms/kg). Straight-leg raising and abdominal compression were used to increase intra-abdominal pressure. Our results show that the increase in LES pressure during straight-leg raising is greater than the increase in gastric pressure. During abdominal compression, the rate of LES pressure increase is faster than that of the gastric pressure, suggesting an active contraction at the esophagogastric junction. The increase in LES pressure during periods of increased intra-abdominal pressure is associated with a tonic contraction of the crural diaphragm as demonstrated by EMG recording. Atropine inhibited the resting LES pressure by 50-70% in each subject but had no effect either on the peak LES pressure attained during increased intra-abdominal pressure or tonic crural diaphragm EMG. We conclude that 1) there is an active contraction at the esophagogastric junction during periods of increased intra-abdominal pressure and 2) tonic contraction of the crural diaphragm is a mechanism for this LES pressure response.
我们研究了腹内压升高对15名健康受试者下食管括约肌（LES）压力的影响。通过测量膈肌肌电图（EMG）来确定膈肌在腹内压升高期间LES压力产生过程中的作用。后者使用双极食管内铂电极记录，该电极放置在套管装置的非压力感应表面上。我们还测量了在静脉注射阿托品（12微克/千克）抑制LES平滑肌时，LES压力对腹内压升高的反应。采用直腿抬高和腹部加压来增加腹内压。我们的结果表明，直腿抬高期间LES压力的增加大于胃内压的增加。腹部加压时，LES压力的增加速率比胃内压快，提示食管胃交界处有主动收缩。腹内压升高期间LES压力的增加与膈肌脚的强直性收缩有关，这通过肌电图记录得到证实。阿托品使每个受试者的LES静息压力降低50% - 70%，但对腹内压升高期间达到的LES峰值压力或膈肌脚强直性肌电图均无影响。我们得出结论：1）腹内压升高期间食管胃交界处有主动收缩；2）膈肌脚的强直性收缩是这种LES压力反应的一种机制。
