去甲肾上腺素介导低氧引起家兔颈动脉体神经电活动增加

HYPOXIA INDUCED INCREASE IN NERVE ACTIVITY OF RABBIT CAROTID BODY MEDIATED BY NORADRENALINE 

在３０ 只家兔颈动脉体窦神经（ＣＳＮ） 标本上， 记录了窦神经中３９ 个对低氧反应敏感的化学感受性单位由去甲肾上腺素（ＮＡ） 及其拮抗剂引起的反应。结果如下：（１） 以低氧的改良台氏液（ＭＴＳ） 灌流标本时，１９ 个单位放电频率由０－１３ ±０－０６ 增至０－２５ ±０－１２ ｉｍｐ／ｓ（ Ｐ＜ ０－００１） ；（２） 在灌流液中加入去甲肾上腺素（１０ － ６ ｍｏｌ／Ｌ） 后，１９ 个单位的自发放电频率由０－１４ ±０－０８ 增至０－２３ ±０－１３ ｉｍｐ／ｓ （ Ｐ＜ ０－０１） ；（３）４ 个自发放电频率为０－１２ ±０－０３ ｉｍｐ／ｓ（ Ｐ＞ ０－０５） 的单位， 在换以含有１０－ ６ ｍｏｌ／Ｌ哌唑嗪ＭＴＳ灌流后， 单位放电频率未见改变；（４）６ 个自发放电频率为０－１２±０－０２ ｉｍｐ／ｓ 的单位， 换以含有１０－ ６ ｍｏｌ／Ｌ育亨宾的ＭＴＳ灌流后，单位放电频率也未见改变；（５） 对３ 例以低氧液灌流时单位放电频率由０－１１ ±０－０３ 增至０－２６±０－１３ｉｍｐ／ｓ（ Ｐ＜ ０－００１） 的标本， 以哌唑嗪（１０－ ６ ｍｏｌ／Ｌ） 预处理后， 再以低氧液灌流时， 单位放电频率由０－１１ ±０－０２ 增至０－３０ ±０－０２ ｉｍｐ／ｓ （ Ｐ?

The responses of 39 hypoxia sensitive units of chemoreceptive afferent in sinus nerve to noradrenaline(NA) and its antagonist were recorded in carotid body sinus nerve preparations from 30 rabbits. The results are as follows. (1) Discharges of the units increased from 0 13±0 06 to 0 25±0 12 imp/s ( P <0 001, n =19) upon lowering PO 2 of modified Tyrode solution. (2) Adding NA(10 -6 mol/L) to the perfusate led to an increase in the unit discharge from 0 14±0 08 to 0 23±0 13 imp/s ( P <0 01, n =19).(3) Prazosin (10 -6 mol/L) did not alter the basal frequency of chemosensory unit discharges under normoxic conditions ( P >0 05, n =4). (4) Yohimbine(10 -6 mol/L) did not alter the basal frequency of chemosensory unit discharges under normoxic conditions ( P >0 05, n =6). (5) Chemosensory responses to hypoxia were not altered after pretreatment with prazosin. (6) Chemosensory responses to hypoxia were inhibited by pretreatment with yohimbine. The present results suggest that (1) NA is not mainly concerned with spontaneous discharges of chemoreceptor sensitive to hypoxia, but does elicit an increase in spontaneous discharges, and (2) the increase of chemosensory unit discharges produced by hypoxia can be inhibited by yohimbine. It is likely that the excitatory action of hypoxia on chemoreceptive process is mediated by NA.