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Effects of stimulation of carotid baro-and chemoreceptor on single unit activity of nucleus iractus solitarius in the cat

Luo Hong, Wang Zhian, Ho Shiuyong

Department of Physiology, Institute of Basic Medicine, Hebei Medical College. Hebei, China

Abstract

The effects of selective activation of carotid baro- and chemoreceptor on the
single unit activity in or nearly the nucleus tractus solitarius (NTS) of caudal medulla were studied in 27 cats under a-chloralose and urethane anesthesia. Of the 103 single units with change of discharge frequency in response to activation of carotid baroreceptor (phenylephrine, 1-2 #mu#g/kg, iv) and/or chemoreceptor (nicotine,5-20 #mu#g, injected into the thyroid artery), 81 were located in NTS, among which 14 responded only to chemoreceptor activation (10 excited and 4 inhibited), 44 with various patterns to both baro- and chemoreceptor activation, and 23 only to baroreceptor activation (18 excited and 5 inhibited). Topographically, the units responsive to both baro- and chemoreceptor activation primarily located in the caudal part of the NTS and the units responsive only to chemoreceptor activation were mainly in the ventrolateral part of NTS, while the remaining units were sparsely distributed in parahypoglossal area,paramedian reticular nucleus and ventral caudal medulla.
In alt the responsive units of the NTS, 67 responded to baroreceptor activation
(excitatory versus inhibitory being 46 to 21) and 58 responded to chemoreceptor
activation (excitatory versus inhibitory being 36 to 22). The significance of the various responsive units of NTS to baro-and chemoreceptor activation was discussed.

Key words: Caretid chemoreceptor;Carotid baroreceptor;Nucleus tractus solitarius;Single unit discharge;Candal medulla

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Citing This Article：

Luo Hong, Wang Zhian, Ho Shiuyong. Effects of stimulation of carotid baro-and chemoreceptor on single unit activity of nucleus iractus solitarius in the cat. Acta Physiol Sin 1987; 39 (5): (in Chinese with English abstract).