Abstract
AbstractIn anaesthetized rats, ventilatory stimulation induced by phentolamine, an α sympatholytic agent, emphasizes the role of some adrenergic mechanisms in the control of the respiratory centres activity.Phentolamine (5 and 10 mg.kg-1, iv) stimulates ventilation after a 4 s latency, tidal volume and respiratory rate being both increased. A same response can also be provoked 10 min later, by a second identical iv administration, systemic blood pressure remaining then stable at its previous low level. Hyperventilation is also observed when phentolamine is injected in totally denervated rats, without any remaining baro- or chemosensitivity. Stimulation is thus due to a central activity in relation with the release of inhibitory influences.Phentolamine also causes hyperventilation after prazosin pretreatment indicating that the α2, adrenergic blockade is not involved in the post-phentolamine stimulation. This is an α2 adrenergic transmission dependent mechanism.Variation of the systemic blood pressure is n...
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