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在低温(14℃)下,用含激动剂的任氏液灌注70只冷服习(3—7℃)蟾蜍的离体心脏和窦房翻转标本,揭示:离体心脏对一系列激动剂正性肌力反应的亲和力顺序为:ISO>E>NA>PHE,甲氧胺则明显压抑心缩力。窦房翻转标本对CA的反应强度顺序为:ISO>E≥NA。PHE作用甚微或无作用。酚妥拉明(4.6—89μM)压抑基础心缩力,但对激动剂的正性肌力效应无影响或暂时抑制。心得安(0.03—0.95μM)对基础心缩力无影响或略压抑,但却抑制CA的正性肌力效应达数小时。在同体上测试,心得安(0.19μM)使E的浓度—效应曲线明显右移,使最大正性肌力50%的E浓度(T_(max)D_(50))值提高近100倍,而酚妥拉明(17.8μM)无此作用。因此,冷服习蟾蜍心脏的正性肌力活动,在低温下,仍受β—受体调控。文中还讨论了在低温下,心得安对冷服习蟾蜍基础心缩力的影响与对CA正性肌力阻滞效应的不一致性。
At a low temperature (14°C), isolated hearts and sinus atrial reversal specimens of 70 cold-bearing (3-7°C) sputum were perfused with Ringer’s solution containing agonist, revealing that the isolated heart was positive for a series of agonists. The order of avidity of the sexual muscular response was: ISO>E>NA>PHE, while methoxyamine significantly suppressed systolic force. The response intensity of sinoatrial reversion specimens to CA was: ISO>E≥NA. PHE has little or no effect. Phentolamine (4.6-89 μM) suppresses the underlying systolic force, but has no effect or temporary inhibition on the inotropic effect of the agonist. Propranolol (0.03-0.95 μM) had no effect on or slightly suppressed the underlying systolic force, but it inhibited the positive inotropic effect of CA for several hours. In a homologous test, propranolol (0.19 μM) significantly shifted the concentration-effect curve of E to the right, which increased the E concentration (T_(max)D_(50)) value of the maximum positive inotropic strength by nearly 100 times. Phentolamine (17.8 μM) does not have this effect. Therefore, the positive inotropic activity of the cold-serving heart is still regulated by β-receptors at low temperatures. The paper also discusses the influence of propranolol on the basic psychological contractility of cold clothing and the inconsistency of CA positive muscle blockade effect at low temperature.