【摘要】 (一)在氯醛糖和氨基甲酸乙酯麻醉的兔或未麻醉的箭毒化兔,右心房内输液(输入量为8—10毫升/公斤,输入速度为0.5—1.0毫升/秒),可规律地引起心率减慢和动脉血压下降。(二)右心房输液引起的心率变化,在切断两对缓冲神经和迷走神经后并不消失,说明此种输液效应并非反射作用。(三)经颈外静脉向右心房内引入一小气囊,以不同压力扩张后,也可导致心率减慢。此时气囊内压值与心率变化之间的关系不是完全呈直线式的。切断迷走神经后,效应仍存在;且此效应也不是由于气囊扩张阻断血液回流所致。(四)以奴佛卡因溶液阻断窦房结区后,右心房输液不再引起心率减慢。全身低温或选择性心脏低温(26—28℃)后,大多数实验中的心率在输液后不再变慢,由此说明右心房内输液对心率的影响是刺激直接作用于窦房结而改变其机能活动的结果。(五)在我们的实验条件下,从兔身上不能证示有 Bainbridge 反射的存在。更多还原

【Abstract】 (1)In the chloralose-urethanized or curarized rabbits,infusion of saline or blood into the right auricle in amount of 8—10 ml/kg at the rate of 0.5—1.0 ml/sec induced bradycardia and hypotension. (2)Section of sino-aortic nerves and bilateral vagotomy did not alter the negative chronotropic effect due to auricular infusion,thus indicating that a local mechanism was responsible for the effect. (3)Distension of the right auricle by inflating an indwelling balloon with various pressures(20—70 mm Hg)also evoked bradyeardia which persisted after cutting the vagi.Plotting the change in heart rate against pressure within the balloon,a non- linear relationship was revealed.The bradycardia observed could not be attributed to anoxemia resulting from reduced venous return,since the temporary occlusion of superior and inferior venae cavae failed to evoke bradycardia. (4)The blockage of sino-auricular node by local novocaine infiltration as well as by local or general hypothermia(26—28℃)abolished the negative chronotropio res- ponse to the atrial infusion.Therefore it was suggested that such a response occurred as a result of alteration in the functional state of sino-auricular node. (5)Under our experimental conditions,the cardiac acceleration reflex originally found by Bainbridge could not be demonstrated in the rabbits.更多还原