Zg. Huang et al., Roles of periaqueductal gray and nucleus tractus solitarius in cardiorespiratory function in the rat brainstem, RESP PHYSL, 120(3), 2000, pp. 185-195
Periaqueductal gray (PAG) and nucleus tractus solitarius (NTS) are importan
t centres for regulation of cardiorespiratory function in cats. We aimed to
study the effects of specific PAG stimulation on cardiorespiratory paramet
ers in the rat. Microinjection of D,L-homocysteic acid (DLH) into dorsolate
ral PAG of anaesthetised rats, led to: marked increases in respiratory freq
uency (RF) and amplitude of diaphragmatic electromyogram, decreases in insp
iratory and expiratory durations, and increased blood pressure and heart ra
te. Following injection of propranolol (150 pmol, 30 nl), a beta-adrenergic
antagonist, into the commissural subnucleus of NTS, the DLH-induced increa
se in RI: was markedly attenuated. Inspiratory neurones (late I cells) in N
TS were excited upon stimulation of PAG and their increased activity was ac
companied by increased RF. The changes in activity of the late I cells in r
esponse to stimulation of dorsolateral PAG provide physiological evidence o
f a link, possibly noradrenergic, between the two nuclei and involvement of
the NTS in control of respiratory functions orchestrated by the PAG. (C) 2
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