CARDIORESPIRATORY REFLEXES IN MICE

The various transgenic strains of mice make this species an attractive experimental model. We compared qualitatively some cardiorespiratory reflexes in two different preparations of mouse: in vivo urethane anae sthetised and a working heart-brainstem preparation (WHBP). Cardioresp iratory reflexes were evoked by stimulating baroreceptors, pulmonary v agal C fibres and cardiac receptors in both preparations, while periph eral chemoreceptors were also stimulated in the WHBP. In anaesthetised mice, activation of baroreceptors, pulmonary C fibres and cardiac rec eptors evoked an atropine-sensitive bradycardia (range: 21-414 bts/min ) and depressed ventilation. A reflex fall in arterial pressure was al so observed during pulmonary C fibre and cardiac receptor stimulation. Similar reflex bradycardia (range 81-164 bts/min) and respiratory res ponses were observed in the WHBP following stimulation of baro-, pulmo nary C fibre and cardiac receptors. Additionally, sodium cyanide stimu lation of peripheral chemoreceptors in the WHBP produced an atropine-s ensitive bradycardia and increased respiratory frequency and amplitude . Thus, the cardiorespiratory reflex responses elicited in the mouse a re similar to those reported in other species. It is concluded that th e qualitatively similar reflex performances between the in vivo anaest hetised mouse and the WHBP make the latter an adequate model for study ing central mechanisms controlling the cardiorespiratory system. (C) 1 998 Elsevier Science B.V.