the results indicate that phentolamine , and alpha-adrenergic blocking drug , does have and ability to partially block induced positive inotropic responses in the canine heart , and perhaps chronotropic responses as well , although propranolol , a beta-blocker , is more effective . the results are in accord with the view that the principal cardiac adrenergic receptors are not adequately described either as classical beta- or alpha-adrenergic receptors .
C0034783
adrenergic receptors
C0034784
alpha-adrenergic receptors