Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, 14049-900, SP, Brazil.
Auton Neurosci. 2010 Dec 8;158(1-2):79-85. doi: 10.1016/j.autneu.2010.06.012. Epub 2010 Jul 23.
In the present study we evaluated the role of purinergic mechanisms in the PVN on the tonic modulation of the autonomic function to the cardiovascular system as well on the cardiovascular responses to peripheral chemoreflex activation in awake rats. Guide-cannulae were bilaterally implanted in the direction of the PVN of male Wistar rats. Femoral artery and vein were catheterized one day before the experiments. Chemoreflex was activated with KCN (80 μg/0.05 ml, i.v.) before and after microinjections of P2 receptors antagonist into the PVN. Microinjection of PPADS, a non selective P2X antagonist, into the PVN (n=6) produced a significant increase in the baseline MAP (99±2 vs 112±3 mmHg) and HR (332±8 vs 375±8 bpm) but had no effect on the pressor and bradycardic responses to chemoreflex activation. Intravenous injection of vasopressin receptors antagonist after microinjection of PPADS into the PVN produced no effect on the increased baseline MAP. Simultaneous microinjection of PPADS and KYN into the PVN (n=6) had no effect in the baseline MAP, HR or in the pressor and bradycardic responses to chemoreflex activation. We conclude that P2 purinoceptors in the PVN are involved in the modulation of baseline autonomic function to the cardiovascular system but not in the cardiovascular responses to chemoreflex activation in awake rats.
在本研究中，我们评估了嘌呤能机制在 PVN 中的作用，即在自主神经功能对心血管系统的紧张性调节以及在清醒大鼠外周化学感受器激活时的心血管反应中。引导套管被双侧植入雄性 Wistar 大鼠的 PVN 方向。股动脉和股静脉在实验前一天进行了导管插入术。在向 PVN 内注射 P2 受体拮抗剂前后，用 KCN（80 μg/0.05 ml，iv）激活化学感受器。向 PVN 内注射非选择性 P2X 拮抗剂 PPADS（n=6）可显著增加基础 MAP（99±2 对 112±3 mmHg）和 HR（332±8 对 375±8 bpm），但对化学感受器激活引起的升压和心动过缓反应没有影响。在向 PVN 内注射 PPADS 后，静脉注射血管加压素受体拮抗剂对基础 MAP 的升高没有影响。同时向 PVN 内注射 PPADS 和 KYN（n=6）对基础 MAP、HR 或对化学感受器激活的升压和心动过缓反应没有影响。我们得出结论，PVN 中的 P2 嘌呤能受体参与了对心血管系统自主神经功能的基础调节，但不参与清醒大鼠外周化学感受器激活时的心血管反应。
