Research on condition of oxygen deficiency in rats

我们对Wistar大鼠缺氧的病理生理学进行了研究。戊巴比妥（60 mg/kg）麻醉后，在氮气、二氧化碳或氦气的缺氧状态下，插管股动脉监测血压、心率并抽血。呼吸停止时间（N_2为15.4±1.5秒，CO_2为19.3±1.8秒，He为17.8±2.4秒）明显短于已发表的狗和兔缺氧实验数据（41 ~ 120秒）。到心脏停止的平均时间：100% CO_2为263±88秒，n2为246±30秒，He为263±88秒。在n2或He诱导的缺氧状态下，直到呼吸停止，我们才发现有不规则的心跳，血压和心率也保持稳定。另一方面，CO_2诱导的缺氧状态平均在5.3秒内引起心律失常，随后血压迅速下降。在n2或He状态下，动脉血气数据显示明显的低氧血症，但没有酸中毒的进展，呼吸停止时没有高碳。在CO_2状态下，由于血压迅速下降，抽取血液样本是困难的。因此，只有少数数据显示在呼吸停止时出现明显的高碳血症和致命的酸中毒。我们认为，N_2和He引起呼吸停滞是由显著的低氧血症引起的，CO_2引起显著的酸中毒，进而影响循环动力学。我们的数据可以解释人类在缺氧状态下猝死的机制。

We examined the patho-physiology of hypoxia in Wistar rats. After anesthetizing with pentobarbital (60 mg/kg), femoral arteries were cannulated for monitoring blood pressure, heart rates and drawing blood samples in a hypoxic state made by nitrogen, carbon dioxide, or helium gas. The time to the respiratory standstill (15.4±1.5 sec in N_2 and 19.3±1.8 sec in CO_2, 17.8±2.4 sec in He) was much shorter than those of the published experimental data of hypoxia using dogs and rabbits (41-120 sec). The average time to the cardiac standstill was 263±88 sec in 100% CO_2 and 246±30 sec in N_2, 263±88 sec in He gas. In N_2 or He induced hypoxic state, we did not recognize any irregular heartbeats until the respiratory standstill, and the blood pressure and the heart rates also remained stable. On the other hand, CO_2 induced hypoxic state caused irregular heartbeats at 5.3 sec on the average, and then the blood pressure decreased rapidly. The arterial blood gas data in a N_2 or He state showed a remarkable hypoxemia but no progress of acidosis and no hypercarbia at the respiratory standstill. In a CO_2 state drawing blood samples is hard because of rapidly falling blood pressure. Therefore, only a few data showed a remarkable hypercarbia and a fatal acidosis at the respiratory standstill. We esteemed that N_2 and He cause the respiratory standstill by a remarkable hypoxemia and CO_2 causes by remarkable acidosis that affects the circulatory kinetics in turn. Our data may explain the mechanism of a very sudden death of human being in an anoxic state.