Park K W, Dai H B, Lowenstein E, Sellke F W
Department of Anesthesia and Critical Care, Beth Israel Hospital, Boston, Massachusetts, USA.
Anesthesiology. 1995 Dec;83(6):1323-30. doi: 10.1097/00000542-199512000-00023.
The authors previously reported that in rabbits, isoflurane exhibited a heterogeneous vasomotor effect, constricting small resistance coronary arteries and dilating larger conductance arteries. The novelty of isoflurane-induced constriction of small coronary arteries raised the question of whether the finding depended on the unique experimental setup or species used. The purpose of this study was to address these questions. Therefore, a second species was studied, namely rats, as well as a second volatile anesthetic, halothane. In addition, the dependence of the vasomotor effect on the preexisting tone of the vessels was examined.
Thirty-six large coronary arteries (262 +/- 23 microns) and 42 small coronary arteries (99 +/- 15 microns) from 31 Wistar rats were isolated. Each vessel was placed in a microvessel chamber and was (1) submaximally preconstricted with the thromboxane analog U46619; (2) submaximally predilated with sodium nitroprusside; or (3) neither preconstricted nor predilated. The vessel was then subjected to increasing concentrations of either isoflurane or halothane, 0-3%. Changes in inner diameter were monitored and recorded with optical density video detection system.
Isoflurane constricted predilated or untreated small coronary arteries, but had no effect on preconstricted small arteries. Isoflurane dilated large coronary arteries, with the preconstricted vessels dilating the most. In contrast, halothane dilated both the small and large coronary arteries to a similar extent. Preconstricted vessels dilated more to halothane than vessels with no added tone.
Whereas isoflurane has a heterogeneous vasomotor effect in rat coronary arteries, constricting the small vessels and dilating the large ones, halothane dilates both the small and large arteries. The vasoconstriction effect was most evident in vessels with no added tone, whereas the vasodilatory effect was most significant in preconstricted vessels.
作者之前报道，在兔中，异氟烷呈现出异质性血管舒缩效应，使小阻力冠状动脉收缩，大传导动脉扩张。异氟烷诱导小冠状动脉收缩这一现象的新颖性引发了一个问题，即该发现是否取决于独特的实验设置或所用物种。本研究的目的是解决这些问题。因此，研究了第二种物种，即大鼠，以及第二种挥发性麻醉剂，氟烷。此外，还研究了血管舒缩效应与血管预先存在的张力之间的关系。
从31只Wistar大鼠分离出36条大冠状动脉（262±23微米）和42条小冠状动脉（99±15微米）。将每条血管置于微血管腔室中，并进行以下处理：（1）用血栓素类似物U46619进行次最大程度的预收缩；（2）用硝普钠进行次最大程度的预扩张；或（3）既不预收缩也不预扩张。然后使血管暴露于浓度逐渐增加的异氟烷或氟烷中，浓度范围为0 - 3%。使用光密度视频检测系统监测并记录内径的变化。
异氟烷使预扩张或未处理的小冠状动脉收缩，但对预收缩的小动脉无影响。异氟烷使大冠状动脉扩张，预收缩的血管扩张最为明显。相比之下，氟烷使小冠状动脉和大冠状动脉扩张的程度相似。预收缩的血管对氟烷的扩张反应比未施加额外张力的血管更大。
异氟烷在大鼠冠状动脉中具有异质性血管舒缩效应，使小血管收缩，大血管扩张，而氟烷使小动脉和大动脉均扩张。血管收缩效应在未施加额外张力的血管中最为明显，而血管舒张效应在预收缩的血管中最为显著。
