CHARACTERISTICS OF C-FIBER BARORECEPTORS IN THE CAROTID-SINUS OF DOGS
CHARACTERISTICS OF C-FIBER BARORECEPTORS IN THE CAROTID-SINUS OF DOGS
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DOI：
10.1113/jphysiol.1987.sp016871
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发表时间：
1987-12-01
影响因子：
5.5
通讯作者：
SCHULTZ, HD
中科院分区：
文献类型：
--
作者：
COLERIDGE, HM;COLERIDGE, JCG;SCHULTZ, HD
1.本文比较了麻醉狗颈动脉窦内C纤维和A纤维压力感受器的压力反应特性，记录了窦神经的冲动和窦内不同的平均压力。通过将窦压逐渐增加到100 mmHg的设定点以上并将其降低到100 mmHg的设定点以下来获得功能性刺激响应曲线。通过与窦压脉动同步的脉动放电识别压力感受器。A和C纤维压力感受器的轴突的传导速度和阻断温度进行了鉴定。2. C和A纤维压力感受器的压力响应特性在几个方面不同。C纤维的搏动放电阈值比A纤维的搏动放电阈值高50毫米汞柱（105.8 ± 0.05毫米汞柱）。1.8和54.6.+-。2.9平均最大灵敏度为A纤维的35%（分别为0.39和1.12脉冲/s~（-1）mmHg~（-1）），最大频率（220 mmHg）为A纤维的29%（分别为24.5和84.3脉冲/s）。虽然总是脉动在阈值以上的压力，C纤维压力感受器的放电模式往往比他们的A纤维同行更不规则。3.还记录了来自C纤维的脉冲，所述C纤维通过增加窦压刺激，但具有不规则的非脉动放电，高压阈值（平均154.1 ± 0.01）。7.2 mmHg），和低的最大频率（10.8 ±. 2.4脉冲/s）。4.冷却窦神经逐渐减弱A和C纤维的传导，A纤维在12 °和4 °之间被阻断。C（平均6.8 ℃）。C）和C纤维在4 °和-1.5 °之间。C（平均1.0 ℃）。C）。尽管将窦神经冷却至7.5 ℃。C并不阻断所有A纤维的传导，压力感受器A纤维在颈动脉窦压力为200 mmHg时的冲动活动并不大于压力为75 mmHg时的冲动活动。相比之下，在7. C压力感受器C纤维仍然提供与窦压成比例的信号。5.我们的研究结果表明，A和C纤维压力感受器subserve不同的反射功能，前者的信号变化在动脉压高于和低于正常设定点，后者只改变以上。他们还建议，差异冷阻滞可能是一个有用的工具，以确定C纤维压力感受器的心血管反射的贡献。
1. We compared the pressure-response characteristics of C fibre and A fibre baroreceptors in the carotid sinus of anaesthetized dogs, recording impulses from the sinus nerve and varying mean pressure in the vascularly isolated sinus, wihch was distended with a pulsatile pressure. Functional stimulus response curves were obtained by gradually increasing sinus pressure above and decreasing it below a setpoint of 100 mmHg. Baroreceptors were identified by a pulsatile discharge synchronous with the pulsations in sinus pressure. A and C fibre baroreceptors were identified by the conduction velocities and blocking temperatures of their axons. 2. The pressure-response characteristics of C and A fibre baroreceptors differed in several respects. C fibres had a pulsatile firing threshold 50 mmHg higher than that of A fibres (105.8 .+-. 1.8 and 54.6 .+-. 2.9 mmHg, respectively), an average maximal sensitivity 35% of that of A fibres (0.39 and 1.12 impulses s-1 mmHg-1, respectively), and a maximal frequency (at 220 mmHg) 29% of that of A fibres (24.5 and 84.3 impulses/s, respectively). Although invariably pulsatile at pressures above threshold, the firing pattern of C fibre baroreceptors tended to be more irregular than that of their A fibre counterparts. 3. Impulses were also recorded from C fibres that were stimulated by increasing sinus pressure but had an irregular, non-pulsatile discharge, a high pressure threshold (averaging 154.1 .+-. 7.2 mmHg), and a low maximum frequency (10.8 .+-. 2.4 impulses/s). 4. Cooling the sinus nerve progressively attenuated conduction in both A and C fibres, A fibres being blocked between 12 and 4.degree. C (mean 6.8.degree. C) and C fibres between 4 and -1.5.degree. C (mean 1.0.degree. C). Although cooling the sinus nerve to 7.degree. C did not block conduction in all A fibres, impulse activity in baroreceptor A fibres at a carotid sinus pressure of 200 mmHg was no greater than that at a pressure of 75 mmHg. By contrast, at 7.degree. C baroreceptor C fibres still provided a signal proportional to sinus pressure. 5. Our results suggest that A and C fibre baroreceptors subserve different reflex functions, the former signalling changes in arterial pressure both above and below the normal set-point, the latter only changes above. They also suggest that differential cold blockade may be a useful tool to determine the contribution of C fibre baroreceptors to cardiovascular reflexes.