Polyamines mediate acute metabolic effects and cardiac hypertrophy associated with β-adrenoceptor stimulation. They may also modulate β-adrenoceptors, causing functional responses in rat atria and tracheal smooth muscle. The aim of this study was to determine whether polyamines interact with human β(1)- and β(2)-adrenoceptors and the functional consequences of such an interaction. Chinese hamst...

The binding affinities of racemic derivatives of propranolol to ƒÀ-adrenoceptors were examined by means of radioligand binding assay to determine whether racemic propranolol shows biphasic binding to ,ƒÀ-adrenoceptors in a displacement experiment. Rat brain was used and the ƒÀadrenoceptor binding assay was carried out with 3H-dihydroalprenolol as the radioligand. A higher affinity of l-proprano...

Changes in the activity of hypothalamic and brain-stem adrenergic neurons have been reported in young spontaneously hypertensive rats (SHR) prior to the development of hypertension. We have measured central alpha- and beta-adrenoceptor concentrations in 4-week-old SHR and Wistar-Kyoto (WKY) controls by direct radioligand binding studies using [3H]prazosin (alpha 1), [3H]clonidine (alpha 2), and...

The specific binding of [ 3 Hlclonidine to a,-adrenoceptors on neural membranes isolated from six brain areas was determined with rats treated for various periods of time with the muscarinic agonists, oxotremorine or pilocarpine, or with the muscarinic antagonists atropine, atropine methyl nitrate, scopolamine and scopolamine methyl bromide. Administration of pilocarpine, 10 mg/kg, twice daily ...

the internal mammary artery (ima) is currently the preferred conduit for myocardial revascularization. however, pre-operative vasospasm and a hypoperfusion state during maximal exercise may limit its use as a bypass graft. the mechanism of spasm has not been clearly defined. since β-adrenoceptor activation plays a major role in vasorelaxation, the present study was carried out to investigate th...

-Adrenoceptors contribute to hypertension in spite of the fact that -adrenoceptor agonists lower blood pressure. We aimed to differentiate between these functions and to identify differences between spontaneously hypertensive and normotensive rats. -Adrenoceptor antagonists with different subtype selectivity or the ability to cross the blood-brain barrier were used to demonstrate -adrenoceptor ...

1. Peptidergic neurones accumulate amines via an unusual uptake process, designated Transport-P. [(3)H]-prazosin binds to alpha(1) adrenoceptors on these cells and is displaceable by unlabelled prazosin in concentrations up to 10(-7) M. However, at greater concentrations of prazosin, there is a paradoxical accumulation of [(3)H]-prazosin which we have attributed to Transport-P. Uptake of prazos...

Kolaj M, Renaud LP. Presynaptic -adrenoceptors in median preoptic nucleus modulate inhibitory neurotransmission from subfornical organ and organum vasculosum lamina terminalis. Am J Physiol Regul Integr Comp Physiol 292: R1907–R1915, 2007. First published January 11, 2007; doi:10.1152/ajpregu.00763.2006.—The median preoptic nucleus (MnPO) in the lamina terminalis receives a prominent catecholam...

Beta3-Adrenoceptors are involved in the control of catecholamine-induced lipolysis in rodent adipose tissues. The expression and function of human beta3-adrenoceptors were investigated in subcutaneous white adipocytes of young healthy women. In these cells, beta3-adrenoceptor mRNAs represent 20% of total amount of beta-adrenoceptor transcripts and less than half of beta1-adrenoceptor transcript...

Sympathetic efferent nerves are present in tendons, but their function within tendon is unknown. alpha(1)-Adrenoceptors are expressed by a variety of cell types. In the presence of norepinephrine (NE), adrenoceptors activate G(q/11) signaling pathways that subsequently increase intracellular Ca(2+) concentration ([Ca(2+)](ic)). It was hypothesized that avian tendon cells express functional adre...