Research Service, Veterans Affairs Medical Center, Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, PO Box 670575, Cincinnati, OH 45267-0575, USA.
Surgical Service, Veterans Affairs Medical Center, The Neuroscience Institute: Department of Neurosurgery, University of Cincinnati College of Medicine, PO Box 670515, Cincinnati, OH 45267-0515, USA.
Respir Physiol Neurobiol. 2014 May 1;195:41-3. doi: 10.1016/j.resp.2014.02.002. Epub 2014 Feb 15.
This study investigated the involvement of sensory nerves and, in particular, neuronal transient receptor potential vanilloid (TRPV) 1 channels, in the CO(2)-mediated regulation of cerebrovascular tone. Basilar artery diameter and blood flow velocity in the ventral midbrain were determined in a rat cranial window preparation by digital imaging and laser-Doppler flowmetry, respectively. Superfusion of the basilar artery with capsaicin, a selective TRPV1 receptor agonist, caused a transient relaxation, consistent with acute desensitization of neuronal TRPV1 channels. Constriction to respiratory hypocapnia remained unaffected following capsaicin superfusion. Denervation of sensory nerves by repeated capsaicin injection of neonates also did not reduce the respiratory hypocapnia constriction of the basilar artery as well as the decreased flow velocity in the ventral midbrain in adults. These findings suggest that sensory nerves and, in particular, neuronal TRPV1 channels, do not play a role in respiratory hypocapnia constriction and decreased flow, at least in rat basilar artery and ventral midbrain.
本研究探讨了感觉神经，特别是神经元瞬时受体电位香草酸（TRPV）1 通道，在 CO2 介导的脑血管张力调节中的作用。通过数字成像和激光多普勒血流测量，分别在大鼠颅窗制备中确定基底动脉直径和腹侧中脑的血流速度。用辣椒素（一种选择性 TRPV1 受体激动剂）灌流基底动脉可引起短暂的松弛，这与神经元 TRPV1 通道的急性脱敏一致。灌流辣椒素后，呼吸性低碳酸血症引起的收缩仍不受影响。通过对新生儿重复注射辣椒素来神经切断，也不能减少成年大鼠基底动脉的呼吸性低碳酸血症收缩以及腹侧中脑的血流速度降低。这些发现表明，感觉神经，特别是神经元 TRPV1 通道，在呼吸性低碳酸血症收缩和血流减少中不起作用，至少在大鼠基底动脉和腹侧中脑中不起作用。
