Central beta-adrenergic effects on the control of ventilation in cats

beta-Adrenergic mimetics and blockers, as well as a local anesthetic (xylocaine) were infused into the vertebral artery of paralyzed and artificially ventilated cats. The effects of the drugs on the central control of ventilation was assessed by measuring the changes in phrenic nerve activity. beta-Mimetics [isoprenaline (1 and 2), metroprolol (1), oxprenolol (1 and 2)] decreased the phrenic nerve activity. beta 2-Mimetics (Salbutamol) and blockers (Butoxamine, H 35/35) had no clear effects. The mode of action of the beta-blockers is most probably not by their local anesthetic properties. It is concluded that beta-adrenergic mechanisms in the brain stem stimulate the ventilatory control system. The receptors are most probably beta 1-receptors.