Abnormalities of Cardiac Sympathetic Nerve Ending Functions in Essential Hypertension

为了阐明原发性高血压时交感神经末梢功能是否受损，我们对麻醉的SHR和WKY大鼠（20周）的左心室心肌进行透析，并监测心肌间质去甲肾上腺素（NE）和二羟基苯乙二醇（DHPG）水平，作为心脏交感神经末梢NE释放和神经元内NE代谢的指标。SHR和WKY之间的心率没有差异，但SHR组平均动脉压、湿心重、血浆NE浓度、血浆DHPG浓度均高于WKY组。SHR组和WKY组心肌间质NE水平无差异，但高K^-和酪胺诱导的间质NE反应SHR组低于WKY组。这些结果表明，SHR 中心脏交感神经末梢的 NE 释放功能受损。 SHR 和 WKY 之间心肌间质 DHPG 水平和地昔帕明（NE 再摄取抑制剂）诱导的间质 NE 反应没有差异。这些结果表明，心脏交感神经末梢的 NE 再摄取和神经元内 NE 代谢功能在 SHR 中是完整的。然后，我们将重点放在支配抵抗动脉的骨骼肌交感神经作为高血浆 NE 和 DHPG 水平的原因。我们对麻醉的SHR和WKY大鼠（20周）的左股骨骨骼肌应用透析技术，监测骨骼肌间质NE和DHPG水平，作为骨骼肌交感神经末梢NE释放和神经元内NE代谢的指标。SHR骨骼肌间质NE水平高于WKY。 SHR 中高 K^- 和酪胺诱导的间质 NE 反应高于 WKY 中的。这些结果表明，SHR 中骨骼肌交感神经末梢的 NE 释放功能增强，这种增强导致血浆 NE 水平升高。 SHR中骨骼肌间质DHPG水平高于WKY，但DHPG/NE比值和地昔帕明诱导的间质NE反应在SHR和WKY之间没有差异。这些结果表明骨骼肌交感神经末梢的 NE 再摄取和神经元内 NE 代谢功能在 SHR 中完好无损。较少的

To elucidate whether sympathetic nerve ending functions are impaired in essential hypertension, we applied dialysis technique to the left ventricular myocardium of anesthetized SHR and WKY rats (20 weeks) and monitored myocardial interstitial norepinephrine(NE) and dihydroxyphenylglycol(DHPG) levels as indexes of NE release and intraneuronal NE metabolism on cardiac sympathetic nerve endings.There was no difference in heart rate between SHR and WKY, but the mean arterial pressure, the weight of wet heart, plasma NE concentration, and plasma DHPG concentration in SHR were higher than those in WKY.There was no difference in myocardial interstitial NE levels between SHR and WKY, but high K^+- and tyramine-induced interstitial NE responses in SHR were lower than those in WKY. These results suggest that NE release function on cardiac sympathetic nerve endings is impaired in SHR. There was no difference in myocardial interstitial DHPG levels and desipramine (NE reuptake inhibitor) -induced i … More nterstitial NE responses between SHR and WKY. These results suggest that NE reuptake and intraneuronal NE metabolic functions on cardiac sympathetic nerve endings are intact in SHR.Then, we focused on skeletal muscle sympathetic nerves innervating resistant arteries as causes of high plasma NE and DHPG levels. We applied dialysis technique to the left femoral skeletal muscle of anesthetized SHR and WKY rats (20 weeks) and monitored skeletal muscle interstitial NE and DHPG levels as indexes of NE release and intraneuronal NE metabolism on skeletal muscle sympathetic nerve endings.Skeletal muscle interstitial NE levels in SHR were higher than those in WKY. High K^+- and tyramine-induced interstitial NE responses in SHR were higher than those in WKY. These results suggest that NE release function on skeletal muscle sympathetic nerve endings is enhanced in SHR and this enhancement contributes to high plasma NE levels. Skeletal muscle interstitial DHPG levels in SHR were higher than WKY, but there was no difference in DHPG/NE ratios and desipramine-induced interstitial NE responses between SHR and WKY. These results suggest that NE reuptake and intraneuronal NE metabolic functions on skeletal muscle sympathetic nerve endings are intact in SHR. Less