Singh R, Ticku M K
Life Sci. 1987 Mar 9;40(10):1017-26. doi: 10.1016/0024-3205(87)90319-5.
This study was conducted to investigate the effects of centrally administered baclofen on blood pressure and heart rate in conscious spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Administration of baclofen (1.0 microgram/kg) into the lateral cerebral ventricle (icv) produced an increase in mean arterial pressure (MAP) in both SHR and WKY rats. The increase in MAP was significantly lower in SHR (13 +/- 3 mmHg) when compared with WKY (27 +/- 5 mmHg). The changes in heart rate (HR) were variable, from no change to a very small increase and did not differ significantly between SHR and WKY rats. The ability of baclofen to interfere with baroreceptor reflexes was also tested in separate experiments. In SHR, icv injection of baclofen (1.0 microgram/kg) significantly suppressed the pressor response and bradycardia evoked by phenylephrine 3.0 micrograms/kg iv, whereas in WKY, the pressor and HR responses to similar injections of phenylephrine were not affected by icv baclofen. Similarly, baclofen treatment modified hypotensive response and reflex tachycardia induced by nitroprusside (10.0 micrograms/kg) iv in SHR but not in WKY rats. Administration of sympathetic ganglionic blocker hexamethonium (HEX; 25 mg/kg) iv produced an equivalent decrease in MAP between SHR and WKY following icv injection of baclofen (1.0 microgram/kg). These results suggest that the effects of baclofen on the baroreceptor reflexes in SHR may not be mediated by a change in peripheral sympathetic tone.
本研究旨在探讨向清醒的自发性高血压（SHR）大鼠和正常血压的Wistar-Kyoto（WKY）大鼠脑室内注射巴氯芬对血压和心率的影响。向脑室内注射巴氯芬（1.0微克/千克）可使SHR大鼠和WKY大鼠的平均动脉压（MAP）升高。与WKY大鼠（27±5 mmHg）相比，SHR大鼠MAP的升高幅度显著较低（13±3 mmHg）。心率（HR）的变化各不相同，从无变化到非常小的增加，且SHR大鼠和WKY大鼠之间无显著差异。在单独的实验中还测试了巴氯芬干扰压力感受器反射的能力。在SHR大鼠中，脑室内注射巴氯芬（1.0微克/千克）可显著抑制静脉注射3.0微克/千克去氧肾上腺素引起的升压反应和心动过缓，而在WKY大鼠中，静脉注射类似剂量去氧肾上腺素时，脑室内注射巴氯芬对升压和心率反应无影响。同样，巴氯芬治疗可改变SHR大鼠静脉注射硝普钠（10.0微克/千克）引起的降压反应和反射性心动过速，但对WKY大鼠无此作用。静脉注射交感神经节阻滞剂六甲铵（HEX；25毫克/千克）后，脑室内注射巴氯芬（1.0微克/千克）可使SHR大鼠和WKY大鼠的MAP产生同等程度的降低。这些结果表明，巴氯芬对SHR大鼠压力感受器反射的影响可能不是由外周交感神经张力的变化介导的。
