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The total and regional peripheral resistance and capacitance of the vascular system is regulated by the sympathetic nervous system, which influences the vasculature mainly through changes in the release of catecholamines from both the sympathetic nerve terminals and the adrenal medulla. The knowledge of the targets for noradrenaline and adrenaline, the main(More)
1. This investigation was undertaken to compare pre- and postjunctional receptors involved in the responses of the canine mesenteric and pulmonary arteries to angiotensin II. 2. In the mesenteric artery, angiotensin II caused an enhancement of tritium overflow evoked by electrical stimulation (EC30% = 5 nM), the maximal effect representing an increase by(More)
Guinea-pig vasa deferentia or hypogastric nerve-vas deferens preparations, preincubated with pargyline (to irreversibly inhibit monoamine oxidase), were exposed to 2.3 μmol/l of unlabelled adrenaline or of 3H-7-(−)-noradrenaline in the presence of hydrocortisone (to inhibit extraneuronal uptake). The vasa deferentia were then mounted in perifusion chambers(More)
The present study was undertaken to analyse the relationship between postnatal development of vascular β2-adrenoceptor-mediated responses and the content of adrenaline in the adrenal gland and its concentration in plasma. Dog saphenous vein tissue from newborn, two-weeks old and adult animals were either preloaded with 3H-noradrenaline (or 3H-adrenaline) to(More)
Rat vasa deferentia were incubated with 0.2 μmol/l 3H-noradrenaline for 60 min and then washed out with amine-free solution for 100 min. Autoradiography then revealed a preferential labelling of the varicosities in the immediate vicinity of the surface of the tissue. However, when tissues were obtained from reserpine-and pargyline-pretreated rats (to block(More)
Imidazolines bind with high affinity not only to α-adrenoceptors but also to specific imidazoline binding sites (IBS) labelled by either [3H]clonidine or [3H]idazoxan and termed I1- and I2-IBS, respectively. Since bovine adrenal chromaffin cells lack α2-adrenoceptors, we investigated the pharmacological characteristics of [3H]clonidine binding sites in the(More)
The aim of the study was to determine the subtype of prejunctional α2-autoreceptors in the canine saphenous vein. Segments of the vein were incubated with 3H-noradrenaline and subsequently perifused with modified Krebs-Henseleit solution. Five periods of electrical stimulation were applied (S1–S5; each for 2min, 1Hz). Concentration-response curves for the(More)
A comparison was made of the influence of candesartan, ZD7155, losartan and eprosartan on angiotensin II effects at pre- and postjunctional AT1 receptors of the rat tail artery. To study the anti-angiotensin II effect at prejunctional receptors, the tissues were preincubated with [3H]noradrenaline and then superfused and electrically stimulated (1 Hz, 2 ms,(More)
Release of 3H-noradrenaline and formation of 3H-metabolites were studied in the saphenous vein of newborn (mean age, 18 h) and adult dogs. Vein strips were incubated with 0.23 μmol/l of 3H-noradrenaline during 1 h and washed out for 110 min; thereafter, the perifusion fluid was collected in 5-min samples. Electrical stimulation was applied at 120 min (1 Hz,(More)
The present study was undertaken to compare the relevance of alpha and beta adrenoceptor-mediated responses at pre- and postjunctional level in the canine saphenous vein of neonates and adults. To quantify prejunctional action, the effect of drugs on the neurogenic outflow of tritium from the vessel loaded previously with [3H]norepinephrine or(More)