We have compared the vasopressor response of alpha-adrenoceptor agonists in young (2 month-old) and older (12 month-old) pithed rats both in the presence and absence of triiodo-L-thyronine (T3)-induced hyperthyroidism. There was no age-related changes in the pressor response to either the alpha 1-selective agonist phenylephrine or the alpha 2-selective agonists clonidine and UK-14,304. However,...

The effects of several beta-adrenoceptor agonists on the relaxation of precontracted human bronchial rings and the inhibition of IgE-mediated histamine release from human lung mast cells (HLMC) were studied. For the relaxation of bronchial rings, isoprenaline, fenoterol and terbutaline were full agonists whereas salbutamol was a full agonist in some (two out of six) experiments and a partial ag...

The alpha2A-adrenoceptor is the prototypic example of the family of G-protein-coupled receptors which function by activation of 'Gi-like' pertussis toxin-sensitive G-proteins. A number of members of this subfamily of G-proteins are often co-expressed in a single cell type. To examine the interaction of this receptor with individual Gi-family G-proteins the porcine alpha2A-adrenoceptor was trans...

We investigated the effects of 2-methyl-5-HT and 1-phenylbiguanide on isolated and perfused rabbit common carotid arteries by a cannula insertion method. 1-Phenylbiguanide produced neither vasoconstriction nor dilation. On the other hand, 2-methyl-5-HT produced only a vasoconstriction, and the dose-response curve was shifted to the right in parallel by treatment with either ketanserin or bunazo...

1 The beta-adrenoceptor agonist isoprenaline normally causes only a small and inconsistent increase in the membrane potential of cells in guinea-pig liver slices, in contrast to the large hyperpolarizations seen with alpha-agonists. However, after a selective alpha-adrenoceptor agonist has been applied, the response to isoprenaline becomes greatly enhanced. 2 Simultaneous application of small d...

b3-Adrenoceptor agonists have recently been introduced for the treatment of overactive urinary bladder syndrome. Their target, the b3-adrenoceptor, was discovered much later than b1and b2-adrenoceptors and exhibits unique properties which make extrapolation of findings from the other two subtypes difficult and the b3-adrenoceptor a less-understood subtype. This article discusses three aspects o...

The aim of this study was to investigate the effect of aerobic exercise training on the lipolytic response of adipose tissue in obese subjects. Thirteen men (body mass index = 36.9 ± 1.3 kg/m2) were submitted to aerobic physical training on a cycloergometer (30-45 min, 4 days a wk) for 3 mo. Adipocyte sensitivity to the action of catecholamines and insulin was studied in vitro before and after ...

beta-Adrenoceptor activation increases intracellular cAMP levels and consequently induces exocytotic amylase release in parotid acinar cells. Phosphodiesterase (PDE) catalyses the hydrolysis of cAMP, which terminates the downstream signaling of this second messenger. We investigated the involvement of PDE4, a cAMP-PDE, in beta-adrenoceptor agonist-induced amylase release in mouse, rat and rabbi...