• 作者： 陳幸一；童吉士；曾興達；陳雪嬌
• 作者服務機構： 國防醫學院生理及生物物理學系
• 中文摘要： 利用經Pentobarbital麻醉及給予Atropine之家兔，探討增加血量及局部牽扯右心房上腔靜脈交界處兩者對於夾閉頸動脈引起感壓反射的作用。由靜脈注射dextran溶液或全血而增加右心房匿（由0.6提高至9.8厘米水柱），此種增加血量輕微升高血壓及降低心跳；局部膨脹小氣球牽扯心房腔靜脈交界處則在切除迷走神經前輕度降低血壓，而切除迷走神經後無顯 著作用。增加血量及局部牽扯兩者均明顯地減弱了感壓反射的升壓反應，對於心速反應則無太大影響。在切除主動脈神經前，感壓反射的升壓反應因增加血量減少了 8.2土1.2毫米水銀（37.4﹪），因局部牽扯減少了9.2土1.6毫米水銀（39.1%)。切除 主動脈神經之後，升壓反應的減弱現象更加明顯，由於增加血量及局部牽扯的減弱分別?18.5±2.1毫米水銀（46.0﹪)及 20.1±1.9毫米水銀（45.7﹪）。增加血量及局部牽扯兩者對感壓反射升壓反應之減弱效應則因切除迷走神經而消失。實驗結果 感壓接受器正常有抑制頸動脈感壓反射升歷反應之作用，但是並不?及增加血量及局部牽扯心房腔靜脈交界處兩 者對於此種升壓反應的減弱效應。頸動脈感藍反射升壓反應的減弱現象乃由於激發心房接?器而經由迷走神經傳入徑引起的結果。
• 英文摘要： In rabbits anesthetized with pentobarbital and pretreated with methyl atropine to block the vagal efferent activity, the effects of volume expansion (ve) and atriocaval balloon inflation (BI) on the common carotid occlusion (cco) responses were studied. ve was achieved by intravenous infusion of dextran solution or blood to raise the right atrial pressure from 0.6 to 9.8 cm h20. The junction between the superior vena cava and right atrium was stretched by inflating a balloon with saline of 0.5 to 0.7 ml. In the intact condition, ve increased the arterial pressure (AP) by 4.5?.8 mm Hg and decreased the heart rate (HR) by ll?.9b/m. It reduced the cco pressor response by 8.2?.2mm Hg (37.4%). BI reduced the AP and HR by 5.3 ?.1 mm Hg and 16?.8b/m and the cco pressor response by 9.2?.6mm Hg (39.1%). The cco tachycardic response was slight before ve or BI and was not significantly altered by ve or BI. After aortic nerves section, ve increased the AP by 8.3 ?.4 mm Hg and decreased the HR by 13?.4b/m. BI reduced the AP and HR by 9.6?.4mm Hg and 20?.2b/m. The cco pressor response was increased two-fold after aortic nerves section. ve and BI attenuated the cco pressor response by 18.5?.1mmHg (46.0%) and 20.1 ?.9 mm Hg (45.7%), respectively. After subsequent cervical vagotomy which interrupts the vagal afferent activity, the cco pressor response was no longer attenuated by either ve or BI. The results indicate that the aortic baroreceptor normally restraints the cco pressor response, but is not involved in the attenuation of the carotid baroreflex pressor response during ve or BI. It appears that the attenuation effects are operated through the vagal afferents subserving the atrial receptors.
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