Studies on uptake and release of sympathomimetic amines

ABSTRACT

Experiments on dogs and cats were performed to determine the similarity in response between bilateral occlusion of common carotid arteries and tyramine. It was found that (1) Alphamethyl tyrosine, an inhibitor of tyrosine hydroxylase, reduced the vasopressor response to occlusion of common carotid arteries as well as to tyramine. (2) Reserpine pretreatment, 24 hours prior to experimentation, abolished the response to carotid clamping as well as to tyramine. (3) Octopamine, a "false neurochemical transmitter" abolished the response to carotid occlusion. (4) Pargyline, a monoamine oxidase inhibitor, reduced the response to carotid occlusion. (5) Infusion of norepinephrine and alpha-methyl norepinephrine into reserpinized preparations restored the vasopressor response to tyramine but octopamine failed to do so. It is suggested that the storage site(s) from which the neurohormones are released during carotid clamping is similar to the site(s) involved in the release of neurohormones by tyramine.