Emerging evidence suggests that G protein coupled receptor 55 (GPR55) may influence adrenoceptor function/activity in the cardiovascular system. Whether this reflects direct interaction (dimerization) between receptors or signalling crosstalk has not been investigated. This study explored GPR55 and alpha 1A-adrenoceptor (α1A-AR) system potential to function/signalling activities. α1A-AR mediate...

1 Cetamolol is a new 3-adrenoceptor blocking agent shown in animals to have moderate PI -adrenoceptor selectivity and partial agonist activity. 2 In healthy normal volunteers, PI -adrenoceptor blockade was measured as the reduction of exercise-induced tachycardia, systolic blood pressure, and double product at 2, 8, and 24 h after a single oral dose of 10, 25, and 50 mg cetamolol. 3 P1-adrenoce...

BACKGROUND There are three turkey β-adrenoceptors: the original turkey β-adrenoceptor from erythrocytes (tβtrunc, for which the X-ray crystal structure has recently been determined), tβ3C and tβ4C-receptors. This study examined the similarities and differences between these avian receptors and mammalian receptors with regards to binding characteristics and functional high and low affinity agoni...

Estrogen receptor-beta knockout mice become hypertensive as they age, and males have a higher blood pressure than females. We hypothesized that the absence of estrogen receptor-beta may contribute to development of cardiovascular dysfunction by modification of adrenergic responsiveness in the peripheral vasculature. Small femoral arteries (internal diameter <200 microm) were isolated from estro...

The present study was designed to measure norepinephrine release during sympathetic nerve stimulation and evaluate the presynaptic inhibitory and facilitatory actions of a-adrenoceptor and /3-adrenoceptor agonists respectively, in the isolated perfused kidney of normotensive WistarKyoto (WKY) and spontaneously hypertensive rats (SHR). Periarterial nerve stimulation (0.25 to 32 Hz) caused a sign...

Human lung fibroblasts are a potential source of endothelin-1 (ET-1), a pro-fibrotic mediator. The present study explored possible muscarinic and β-adrenergic modulations of ET-1 expression in human lung fibroblasts. MRC-5 human lung fibroblasts were cultured. Expression of prepro-endothelin-1 (ppET-1) mRNA was determined by quantitative real time PCR. [(3)H]-Proline incorporation was determine...

In rat locus coeruleus (LC) neurons, alpha 2 adrenoceptors, mu-opioid and somatostatin receptors all activate the same potassium conductance. Chronic treatment with morphine causes a loss of sensitivity that is specific to the mu-opioid response, with no change in the alpha 2 adrenoceptor-mediated response. Acute desensitization induced by opioid, somatostatin, and alpha 2-adrenoceptor agonists...

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...

Since 20 years the concept of specific imidazoline receptors has remained controversial. The problem with imidazoline receptors is mostly due to their functional similarity to alpha-adrenoceptors. In this work, a pharmacodynamic model of isolated rat jejunum longitudinal muscle strips constricted with acetylcholine (Ach) was applied to separate functional properties of the two types of receptor...