Pimentel Franklin F, Bonagamba Leni G H, Machado Benedito H
Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil.
Am J Physiol Regul Integr Comp Physiol. 2003 Apr;284(4):R1000-9. doi: 10.1152/ajpregu.00310.2002. Epub 2002 Dec 5.
Microinjection of glycine into the rostral (bilateral) and caudal (midline) commissural nucleus of the solitary tract (NTS) using three guide cannulas implanted in the direction of these sites produced an increase in mean arterial pressure (MAP) and abolished the pressor response to chemoreflex activation [potassium cyanide (n = 7)]. Strychnine, a glycine receptor antagonist, attenuated the increase in MAP, and in this new experimental condition (n = 5) the pressor response to chemoreflex activation was not altered. Considering that the effect of glycine on the attenuation of the pressor response to chemoreflex activation could be secondary to the increase in baseline MAP, in a third group of rats (n = 5) sodium nitroprusside infusion (intravenous) after microinjections of glycine into the NTS normalizes MAP. In this case, the pressor response to chemoreflex activation was similar to the control. These data show that glycine when microinjected bilaterally into the lateral commissural NTS as well as into the medial commissural NTS plays no major inhibitory role in the processing of the neurotransmission of the sympathoexcitatory component of the chemoreflex.
使用三根朝着这些部位植入的引导套管，将甘氨酸微量注射到孤束核（NTS）的吻侧（双侧）和尾侧（中线）连合核中，导致平均动脉压（MAP）升高，并消除了对化学反射激活[氰化钾（n = 7）]的升压反应。士的宁是一种甘氨酸受体拮抗剂，它减弱了MAP的升高，并且在这种新的实验条件下（n = 5），对化学反射激活的升压反应没有改变。考虑到甘氨酸对化学反射激活的升压反应减弱的作用可能继发于基线MAP的升高，在第三组大鼠（n = 5）中，在将甘氨酸微量注射到NTS后静脉输注硝普钠可使MAP恢复正常。在这种情况下，对化学反射激活的升压反应与对照组相似。这些数据表明，当将甘氨酸双侧微量注射到外侧连合NTS以及内侧连合NTS中时，它在化学反射的交感兴奋成分的神经传递过程中不发挥主要抑制作用。
