Labelled tyramine glucuronide was synthesized in vitro from UDP-[14C]glucuronic acid, [14C]tyramine or [3H]tyramine. The glucuronidation was carried out at pH9.2 in the presence of a monoamine oxidase inhibitor, trans-2-phenylcyclopropylamine. The Km values for tyramine were 69 and 125 micrometer and those for UDP-glucuronic acid were 260 and 290 micrometer respectively for guinea-pig and rat l...

An immunohistochemical method using biotinyl tyramine was recently introduced to amplify weak staining signals. Despite its high sensitivity, however, tyramine-based immunostaining has been limited by its increased background staining. In this study, to develop an improved protocol of biotinyl tyramine-based immunohistochemistry minimizing the background staining, we determined which staining s...

The isolated right atrium of the dog was perfused with arterial blood introduced from a carotid artery of a support dog. The selective injection of dopamine, tyramine and norepinephrine into the cannulated sinus node artery induced dose-relatedly positive chronotropic and inotropic effects. However, for an equal increase in sinus rate, dopamine caused less increase in tension development than n...

Hypertyraminemia is common in hepatic cirrhosis and correlates in severity with encephalopathy. The mechanism of cirrhotic hypertyraminemia has not been established. The alternative possibilities are increased production from tyrosine and impaired degradation by monoamine oxidase. This investigation determined the pharmacokinetics of tyramine after an intravenous bolus injections of [3H]-tyrami...

THE oxidation of tyramine in the liver has been investigated in vivo by Ewins & Laidlaw [1910] and in vitro by Hare [1928] and Bernheim [1931]. The former workers found that in feeding and liver perfusion experiments tyramine disappeared and p-hydroxyphenylacetic acid could be recovered from the urine and perfusates. Hare and Bernheim, using the Barcroft and Warburg manometric techniques, studi...

Ewins and Laidlaw (1) showed that tyramine disappeared when perfused through the heart, liver, or uterus of rabbits and cats. The amine oxidase, which deaminates tyramine and many other primary amines, has been studied in liver and kidney (2) but no further observations have been made on the fate of tyramine in the heart or other muscle. In particular it is not known whether muscle is able to d...

Episodes of atrial fibrillation that occurred after meals developed in a 60 year old man with a history of ischaemic heart disease. The attacks were precipitated by precursors and metabolites of tyramine and tyramine containing foods and drinks, in the absence of monoamine oxidase inhibitors. The patient has remained free of atrial fibrillation for the past twelve months on a diet that does not...

The role of octopamine and tyramine in regulating spontaneous contractions of reproductive tissues was examined in the female Rhodnius prolixus Octopamine decreased the amplitude of spontaneous contractions of the oviducts and reduced RhoprFIRFa-induced contractions in a dose-dependent manner, whereas tyramine only reduced the RhoprFIRFa-induced contractions. Both octopamine and tyramine decrea...

Octopamine (OA) is present in insect nervous tissue, but little is known about its biosynthesis. In the CNS of Manduca sexta, OA levels increase markedly during postembryonic adult development. To study this increase, we developed an assay for tyramine-beta-hydroxylase, the putatively rate-limiting enzyme for OA biosynthesis. Tyramine-beta-hydroxylase activity in extracts of M. sexta CNS tissue...

Rasagiline is an irreversible monoamine oxidase type B (MAO-B) inhibitor indicated for the treatment of the signs and symptoms of idiopathic Parkinson disease as initial monotherapy and as adjunct therapy to levodopa. Pharmacologic inhibition of monoamine oxidase type A (MAO-A), but not MAO-B, poses a risk of the "cheese effect," a hypertensive response to excess dietary tyramine, a biogenic sy...