[Role of sGC-cGMP pathway in CO-mediated regulation of respiratory rhythm].
OBJECTIVE
To identify the role of soluble guanylyl cyclase-cyclic guanine monophosphate (sGC-cGMP) pathway in the carbon monoxide (CO) mediating regulation of respiratory rhythm from the medulla oblongata.


METHODS
Medullary slices of newborn Sprague-Dawley rats were prepared for the experiment. The electrophysiological experiment comprised 5 groups (each with 8 slices), each of which were perfused with artificial cerebrospinal fluid (ACSF control group), CO (exogenous CO group), 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (a specific inhibitor of sGC, ODQ group), ODQ+CO (ODQ+CO group), and dimethyl sulfoxide (vehicle of ODQ, DMSO group), respectively. The burst frequency (BF) of hypoglossal rootlets was recorded as an index of rhythmic respiratory activity. Radioimmunoassay was employed to determine cGMP levels of the medullary slices of the ACSF control group, exogenous CO group, ODQ group and ODQ+CO group (n=6/ group).


RESULTS
The exogenous CO decreased the BF (P < 0.05) and increased the cGMP level (P < 0.05). The ODQ increased the BF (P < 0.05) and decreased the cGMP level (P < 0.05). No significant changes were found in the BF and cGMP levels when CO and ODQ applied simultaneously (P > 0.05), but the BF increased (P < 0.05) after the drug perfusion ended.


CONCLUSIONS
sGC-cGMP pathway may play an important role in the CO mediated regulation of respiratory rhythm from the medulla oblongata.
Zhang
Qi-lan
QL
Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, China.
Yang
Wen-xing
WX
Zhou
Hua
H
Sun
Xue-chuan
XC
Shi
Yu-jian
YJ
Chen
Qi
Q
Zheng
Yu
Y
D000818:Animals; D000831:Animals, Newborn; D002248:Carbon Monoxide / Q000494:pharmacology*; D006152:Cyclic GMP / Q000378:metabolism*; D055724:Electrophysiological Phenomena / Q000187:drug effects; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism*; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D010507:Periodicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012119:Respiration / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D000071756:Soluble Guanylyl Cyclase
D018160:Receptors, Cytoplasmic and Nuclear; D002248:Carbon Monoxide; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D006152:Cyclic GMP