Orer H S, Barman S M, Gebber G L
Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michican 48824, USA.
Am J Physiol Heart Circ Physiol. 2001 Aug;281(2):H613-22. doi: 10.1152/ajpheart.2001.281.2.H613.
This study was designed to test the hypothesis that 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) and clonidine reduce sympathetic nerve discharge (SND) and mean arterial pressure (MAP), in part by actions in the medullary lateral tegmental field (LTF). We microinjected these drugs bilaterally into the LTF of baroreceptor-innervated and -denervated cats anesthetized with Dial-urethane. Neither drug altered SND (as quantified by using power spectral analysis) or MAP when injected into the LTF of baroreceptor-denervated cats. However, cardiac-related power in SND was significantly increased to 148 +/- 12 (mean +/- SE) and 149 +/- 5% of control by microinjections of 8-OHDPAT (n = 5) and clonidine (n = 5), respectively, in baroreceptor-innervated cats whose MAP was kept constant; there was no change in 0- to 6-Hz power or total power. SND was significantly reduced by microinjection of these drugs into the rostral ventrolateral medulla of baroreceptor-innervated and -denervated cats. In conclusion, although 8-OHDPAT and clonidine did not reduce SND when injected into the LTF, they acted in this region to facilitate baroreceptor reflex control of SND, as evidenced by a selective increase in cardiac-related power.
8-羟基-2-（二正丙基氨基）四氢萘（8-OHDPAT）和可乐定可降低交感神经放电（SND）和平均动脉压（MAP），其部分作用是通过在延髓外侧被盖区（LTF）发挥作用实现的。我们将这些药物双侧微量注射到用二乙烯脲麻醉的、有压力感受器支配和无压力感受器支配的猫的LTF中。当将这两种药物注射到无压力感受器支配的猫的LTF中时，均未改变SND（通过功率谱分析进行量化）或MAP。然而，在MAP保持恒定的有压力感受器支配的猫中，分别微量注射8-OHDPAT（n = 5）和可乐定（n = 5）后，SND中与心脏相关的功率显著增加至对照的148±12（平均值±标准误）和149±5%；0至6Hz功率或总功率无变化。将这些药物微量注射到有压力感受器支配和无压力感受器支配的猫的延髓头端腹外侧时，SND显著降低。总之，虽然将8-OHDPAT和可乐定注射到LTF中时并未降低SND，但它们在该区域发挥作用以促进压力感受器对SND的反射控制，这一点可通过与心脏相关的功率选择性增加得到证明。
