Suppression of inspiratory fast rhythm, but not bilateral short-term synchronization, by morphine in anesthetized rabbit.
To better understand the involvement of opioid receptor systems in the respiratory control, effects of morphine on the high-frequency component of inspiratory nerve discharge were evaluated. The inspiratory fast rhythm in the bilateral phrenic nerve discharge of anesthetized and artificially ventilated rabbits was analyzed with power spectral and coherence functions. Morphine (0.625-10 mg/kg, i.v.) decreased the amplitude and frequency of the inspiratory fast rhythm in a dose-dependent manner via naloxone-sensitive mechanisms. In contrast, the bilateral short-time scale correlation of the phrenic fast rhythm was resistant to morphine even at a strong suppression of the respiratory activities. It is concluded that there is little influence of opioid receptor system to the neural connectivity underlying bilateral phrenic synchronization.
Kato
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Department of Pharmacology II, Jikei University School of Medicine, Tokyo, Japan. fusao@jikei.ac.jp
D000818:Animals; D019771:Axotomy; D004305:Dose-Response Relationship, Drug; D007839:Functional Laterality; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009476:Neurons, Efferent / Q000502:physiology; D010507:Periodicity; D010791:Phrenic Nerve / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012119:Respiration / Q000187:drug effects*; D012815:Signal Processing, Computer-Assisted
D009270:Naloxone; D009020:Morphine