M3-receptor activation counteracts opioid-mediated apneusis, but the apneusis per se is not necessarily related to an impaired M3 mechanism in rats

Blockade of phosphodiesterase 4 reverses morphine-induced ventilatory disturbance without loss of analgesia

“…The experiment was performed according to our previous report [28]. Male Wistar rats (300-550 g) were anesthetized intraperitoneally with a mixture of urethane (1.0 g/kg) and α-chloralose (25.0 mg/kg).…”