The goal of this study was to examine the effects of systemic morphine on the pattern and morphology of gasping breathing during respiratory autoresuscitation from transient anoxia. We hypothesized that systemic morphine levels sufficient to cause significant depression of eupnea, would also cause depression of gasping breathing. Respiratory and cardiovascular variables were studied in twenty spontaneously breathing, pentobarbital-anaesthetized adult male rats. Sham (saline) injections caused no significant change in resting respiratory or cardiovascular variables (n=10). Morphine, on the other hand, caused significant depression of eupneic breathing, with ventilation and peak inspiratory flow decreased by ~30 to 60%, depending on the background condition (n=10). In contrast, morphine did not affect depress gasping breathing. Duration of primary apnea, time to restore eupnea, the number and amplitude of gasping breaths, average and maximum peak flows and volume of gasping breaths were not significantly different post-injection in either condition. Blood pressures were all significantly lower following morphine injection at key time points in the process of autoresuscitation. Lastly, rate of successful recovery from anoxia was 80% in the morphine group (8/10) compared to 100% (10/10) in the sham group, post-injection. We conclude that the mechanisms and/or anatomic correlates underlying generation of gasping rhythm are distinct from those underlying eupnea, allowing gasping to remain robust to systemic morphine levels causing significant depression of eupnea. Morphine nevertheless decreases likelihood of recovery from transient anoxia, possibly as a result of decreased tissue perfusion pressures at critical time points during the process of respiratory autoresuscitation.

中文翻译：

---

吗啡对麻醉的自发呼吸成年大鼠的呼吸和喘息作用的差异。

这项研究的目的是研究全身性吗啡对短暂性缺氧引起的呼吸自动复苏过程中喘气的模式和形态的影响。我们假设全身性吗啡水平足以引起显着的通气抑制，也会引起呼吸喘息。研究了二十只自发呼吸，戊巴比妥麻醉的成年雄性大鼠的呼吸和心血管变量。假（盐水）注射不会引起静息呼吸或心血管变量的显着变化（n = 10）。另一方面，吗啡会导致严重的紫红色呼吸抑制，通气和峰值吸气量下降约30％至60％，具体取决于背景条件（n = 10）。相比之下，吗啡对抑郁的呼吸没有影响。在任何一种情况下，注射后原发性呼吸暂停的持续时间，恢复呼吸暂停的时间，喘气的次数和幅度，平均和最大峰值流量以及喘气的量均无显着差异。在自动复苏过程中的关键时间点注射吗啡后，血压均显着降低。最后，注射后，吗啡组（8/10）的缺氧成功恢复率为80％，而假手术组为100％（10/10）。我们得出结论，潜在的喘气节律产生的机制和/或解剖学相关性与潜在的气喘病截然不同，从而使喘气保持对全身吗啡水平的稳健性，从而引起明显的气喘。然而，吗啡降低了从短暂性缺氧中恢复的可能性，