Effects of microinjection of L-glutamate into locus coeruleus complex area on respiration.
The experiments were performed on 55 rabbits vagotomied, anesthetized with urethane and immobilized with flaxedil. Injection of L-glutamate (L-glu) into the locus coeruleus complex (Lc-Sc) area led to a marked increase in respiratory frequency (RF) and phrenic nerve discharge rate (phr.d) (16 +/- 3.5% and 6.5 +/- 2.5%; P < 0.01 and P < 0.05, respectively), a decrease in inspiratory and expiratory duration, and no obvious change in blood pressure (Bp) was observed. While prazosin (0.5 micrograms/microliters), yohimbin (4 micrograms/microliters) and propranolol (2 micrograms/microliters) were preinjected into the nuclei tractus solitraii (NTS) respectively, the above-mentioned effects of L-glu on respiration was blocked. These results indicate that the excitation of neurons in the Lc-Sc can induce an increase in RF and phr. d and the excitative effect of L-glu on RF was mediated by alpha 1, alpha 2 and beta-receptors in the NTS, while the effect on phr.d was mediated differently.
Li
Z Y
ZY
Department of Physiology, Tongji Medical University, Wuhan.
Xia
B L
BL
Huang
C J
CJ
D000818:Animals; D005971:Glutamates / Q000494:pharmacology*; D008125:Locus Coeruleus / Q000502:physiology*; D008845:Microinjections; D009474:Neurons / Q000502:physiology; D011817:Rabbits; D012119:Respiration / Q000187:drug effects*
D005971:Glutamates