Takemoto Y
Department of Physiology, Hiroshima University School of Medicine, Minami-ku, Japan.
Jpn J Physiol. 1995;45(5):771-83. doi: 10.2170/jjphysiol.45.771.
The hemodynamic effects of intracisternal injection of the nonessential amino acid L-cysteine were studied in conscious chronically instrumented rats. Injections of L-cysteine (0.05-0.2 M in artificial cerebrospinal fluid, 10 microliters) into the cisterna magna dose-relatedly elicited an increase in arterial pressure but a decrease in superior mesenteric blood flow as measured by an electromagnetic flow probe. Injections of the excitatory amino acid transmitter L-glutamate at comparable doses caused much the same pressor and vasoconstrictor effects as did L-cysteine. Prior I.V. injection of vasopressin V1-receptor antagonist, (d(CH2)5(1), O-Me-Tyr2, Arg8)-vasopressin (10 micrograms/kg), markedly attenuated the effects of L-glutamate but not of L-cysteine. Ganglionic blockade with chlorisondamine (5.0 mg/kg) failed to attenuate the effects of either amino acid, whereas an additional intravenous injection of vasopressin antagonist, completely abolished the effects. These results indicate that the circulatory effects of L-cysteine are probably due to autonomic nervous activation combined with vasopressin release, unlike those of L-glutamate which acts mainly through vasopressin release. L-Cysteine may contribute to central cardiovascular control, since it induces the marked circulatory effects comparable to or greater than those of L-glutamate.
在清醒的、长期植入仪器的大鼠中研究了脑池内注射非必需氨基酸L-半胱氨酸的血流动力学效应。向大鼠脑大池注射人工脑脊液中浓度为0.05-0.2M的L-半胱氨酸（10微升），剂量依赖性地引起动脉血压升高，但通过电磁血流探头测量发现肠系膜上血流量减少。注射同等剂量的兴奋性氨基酸递质L-谷氨酸，引起的升压和血管收缩效应与L-半胱氨酸大致相同。预先静脉注射血管加压素V1受体拮抗剂（d(CH2)5(1), O-Me-Tyr2, Arg8)-血管加压素（10微克/千克），可显著减弱L-谷氨酸的效应，但对L-半胱氨酸的效应无影响。用氯异吲哚铵（5.0毫克/千克）进行神经节阻断，未能减弱任何一种氨基酸的效应，而额外静脉注射血管加压素拮抗剂则完全消除了这些效应。这些结果表明，L-半胱氨酸的循环效应可能是由于自主神经激活并伴有血管加压素释放，这与主要通过血管加压素释放起作用的L-谷氨酸不同。L-半胱氨酸可能参与中枢心血管控制，因为它诱导的明显循环效应与L-谷氨酸相当或更强。
