Actions of glucagon on the perfused vessels of the isolated rabbit ear

Actions of glucagon on the perfused vessels of the isolated rabbit ear were investigated. The two main actions of glucagon on the perfused ear vessels of the rabbit are: (i) release of noradrenaline which accounts for the constrictor response in low tone preparations. The response depends on the level of 3, 5 AMP. If the level rises as a result of noradrenaline action, contriction sets in. (ii) Glucagon may stimulate the adenylcyclase. In the high tone preparation 3,5 AMP levels are probably high. Release of noradrenaline by glucagon would have little additonal effect.