Mechanism of isoprenaline induced desensitization of rabbit aortic smooth muscle beta-adrenoceptor responses.

The effects of short term (1 h) as well as prolonged (16 h) activation of beta-adrenoceptors by isoprenaline on the functioning of the beta-adrenoceptor linked adenylate cyclase system of rabbit aortic smooth muscle cells in the contractile phenotype in primary culture was examined. Smooth muscle cells responded to 50 mumol/l isoprenaline with a rapid increase in intracellular cAMP. Continued exposure of these cells to this concentration of isoprenaline results in a rapid time dependent reduction in maximum beta-adrenoceptor responsiveness.

Effects of noradrenergic neuronal activity on 3,4-dihydroxyphenylethylene glycol (DHPG) levels. Quantitation by high performance liquid chromatography.

We describe a sensitive specific and simple high pressure liquid chromatographic procedure for determining 3,4-dihydroxyphenyl-ethylene glycol (DHPG) in both plasma and tissue. DHPG is extracted from plasma or tissue extracts by adsorption onto alumina. DHPG in the alumina eluate is detected electrochemically following chromatography on a C18 reverse phase column.

Bioavailability of dihydroergotamine in man.

1 The pharmacokinetics of dihydroergotamine (DHE) in plasma were examined in six normotensive subjects after single acute doses of dihydroergotamine, 10 micrograms/kg i.v. and 10, 20 and 30 mg orally.

The peripheral kinetics of norepinephrine in depressive illness.

Sympathetic nervous system function was studied in patients with primary depressive illness. Tritiated norepinephrine was used to measure the rate of entry to plasma of norepinephrine released from sympathetic nerves ("norepinephrine spillover rate"), and to assess the neuronal uptake of norepinephrine by studying the removal of norepinephrine from plasma. Norepinephrine spillover was elevated in five of 11 patients.