Karius D R, Ling L M, Speck D F
Department of Physiology, University of Kentucky Medical Center, Lexington, 40536-0084.
Am J Physiol. 1991 Dec;261(6 Pt 1):L443-8. doi: 10.1152/ajplung.1991.261.6.L443.
Previous studies have indicated that excitatory amino acids are involved in many afferent pathways. This study investigated the effects of intravenous MK-801 [an N-methyl-D-aspartate (NMDA) receptor-associated channel blocker] on several well-known respiratory reflexes elicited by afferent stimulation of the superior laryngeal (SLN), the intercostal (ICN), and the phrenic (PN) nerves. Control responses to stimulation were obtained from recordings of phrenic nerve activity in decerebrate, paralyzed cats. Inspiratory termination elicited by the delivery of stimulus trains to either the SLN or the ICN persisted after MK-801. The onset latency or duration of the short-latency excitations produced by SLN or ICN stimulation were unchanged. The transient inhibitions produced by SLN, ICN, PN, or medullary stimulation showed no significant changes in threshold, onset latency, or duration. Withholding lung inflation produced apneusis after administration of MK-801, indicating a central effect of the drug. Higher doses of MK-801 did not alter the parameters of these reflexes. These data indicate that NMDA-dependent neurotransmission is not required for the production of these reflexes.
先前的研究表明，兴奋性氨基酸参与了许多传入通路。本研究调查了静脉注射MK-801[一种N-甲基-D-天冬氨酸（NMDA）受体相关通道阻滞剂]对由喉上神经（SLN）、肋间神经（ICN）和膈神经（PN）传入刺激引发的几种知名呼吸反射的影响。通过记录去大脑、麻痹猫的膈神经活动获得对刺激的对照反应。向SLN或ICN输送刺激串引发的吸气终止在注射MK-801后持续存在。SLN或ICN刺激产生的短潜伏期兴奋的起始潜伏期或持续时间没有变化。SLN、ICN、PN或延髓刺激产生的短暂抑制在阈值、起始潜伏期或持续时间上没有显著变化。在注射MK-801后，停止肺充气会产生呼吸暂停，表明该药物具有中枢效应。更高剂量的MK-801并未改变这些反射的参数。这些数据表明，产生这些反射不需要NMDA依赖性神经传递。
