Weaver L C, Akera T, Brody T M
J Pharmacol Exp Ther. 1977 Jan;200(1):141-6.
Digitalis increases phrenic nerve activity and causes hyperventilation. To determine whether this effect on respiration is caused by central drug actions on brainstem respiratory neurons or by peripheral drug actions which increase excitatory afferent drive to central respiratory neurons, digoxin was administered intravenously to cats with or without intact IXth and Xth cranial nerves. Digoxin caused marked increases in phrenic nerve activity in cats with intact afferent cranial nerves, but it had no effect in cats with severed afferent nerves. This suggested that effects of digoxin on respiration depend upon afferent input to respiratory neurons. However, digoxin may have had subliminal effects on central neurons which increased phrenic activity only in the presence of excitatory input. To test this possibility, effects of intravenously administered digoxin were observed on centrally evoked submaximal responses in the phrenic nerve. Subarrhythmic, arrhythmic or lethal doses of digoxin had no effect on excitatory phrenic responses evoked from the pons. Thus, effects of digoxin on phrenic nerve activity appeared to be due primarily to drug actions on peripheral neural sites which had excitatory influences on respiration.
洋地黄可增加膈神经活动并导致通气过度。为了确定这种对呼吸的影响是由药物对脑干呼吸神经元的中枢作用引起的，还是由增加对中枢呼吸神经元的兴奋性传入驱动的外周药物作用引起的，将地高辛静脉注射给有或没有完整第九和第十对脑神经的猫。地高辛使传入脑神经完整的猫的膈神经活动显著增加，但对传入神经切断的猫没有影响。这表明地高辛对呼吸的影响取决于对呼吸神经元的传入输入。然而，地高辛可能对中枢神经元有阈下作用，仅在存在兴奋性输入时才增加膈神经活动。为了检验这种可能性，观察了静脉注射地高辛对膈神经中枢诱发的次最大反应的影响。亚心律失常、心律失常或致死剂量的地高辛对脑桥诱发的膈神经兴奋性反应没有影响。因此，地高辛对膈神经活动的影响似乎主要是由于药物对外周神经部位的作用，这些部位对呼吸有兴奋性影响。
