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Adrenoreceptor Antagonist (adrenoreceptor + antagonist)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Isoxsuprine hydrochloride in the horse: a review

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2002
R. S. ERKERT
Isoxsuprine hydrochloride has been suggested for use in horses for treatment of navicular syndrome and laminitis. The drug has been shown to be a , -adrenoreceptor antagonist with , -adrenoreceptor agonistic properties, with both characteristics contributing to vasodilation and uterine relaxation. In addition, the drug is capable of decreasing blood viscosity and platelet aggregation. Studies have shown i.v. isoxsuprine to have a plasma half-life of <3 h with a large apparent volume of distribution. Cardiovascular effects resolve rapidly following i.v. administration, but are absent with oral dosing. Oral bioavailability is 2.2% with a high first pass effect. Isoxsuprine has an apparent affinity for melanin that may contribute to extended renal excretion. Clinical trials appear to support the use of isoxsuprine for treatment of navicular disease. However, poor bioavailability, lack of cardiovascular effects following oral administration, superficial support in clinical trials, and new evidence regarding the pathogenesis of navicular syndrome indicate that the use of isoxsuprine for treatment of navicular syndrome or laminitis is questionable at best. [source]

Noradrenergic Control of Arginine Vasopressin Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol

REPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2008
SPS Ghuman
Contents The present study aims at ascertaining the influence of ,1 -adrenoreceptors on arginine vasopressin (AVP) release in vitro and determine whether E2 modulates the ,1 -adrenoreceptor and AVP interaction. Ten minutes after ewe killing, sagittal midline hypothalamic slices (from the anterior preoptic area to the mediobasal hypothalamus with the median eminence, 2 mm thick, 2 per sheep) were dissected, placed in oxygenated minimum essential media- , (MEM- ,) at 4°C and within 2 h were singly perifused at 37°C with oxygenated MEM- , (pH 7.4; flow rate 0.15 ml/min), either with or without E2 (24 pg/ml). After 4 h equilibration, 10 min fractions were collected for 4 h interposed with 10 min exposure at 60 min to a specific ,1 -adrenoreceptor agonist or antagonist at various doses (0.1,10 mm). At the end of all perifusions, slices responded to KCl (100 mm) with AVP efflux (p < 0.05). Release of AVP was enhanced (p < 0.05) by the ,1 -adrenoreceptor agonist (methoxamine 10 mm; no E2, n = 7 perifusion chambers: from 14.3 ± 2.7 to 20.9 ± 3.9, with E2, n = 10: from 10.7 ± 1.2 to 18.4 ± 3.4 pg/ml) or the antagonist (thymoxamine 10 mm; no E2, n = 5: from 9.5 ± 3.1 to 30.4 ± 6.0, with E2, n = 10: from 10.8 ± 0.9 to 39.1 ± 6.3 pg/ml). With the agonist, the response occurred only at 80 min (p < 0.05) both in the presence and absence of E2. Whereas, after the antagonist, values were higher (p < 0.05) throughout the post-treatment period (80,170 min) without E2, but declined by 150 min in the presence of E2. Furthermore, the response to the ,1 -adrenoreceptor antagonist was greater (p < 0.05; 90,140 min) than the agonist only in the presence of E2. In conclusion, these results reveal direct ,1 -adrenoreceptor-mediated control of the hypothalamic AVP neuronal system which is modulated by E2. [source]

Administration of noradrenaline in the autonomic ganglia modifies the testosterone release from the testis using an ex vivo system

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 4 2009
Zulema Y. Sosa
Summary The male gonad receives nerve fibres from the autonomic ganglionic system. These fibres converge on the testis along two pathways, the superior and the inferior spermatic nerves. The superior spermatic nerve runs from the superior mesenteric ganglion alongside the testicular artery, whereas the inferior spermatic nerve originates in inferior mesenteric ganglion, accompanies the vas deferens and penetrates the inferior pole of the testis. The aim of this work was to evaluate androgen release after the addition of noradrenaline or adrenoreceptor antagonists (propranolol or phentolamine) to the ganglionic compartment. An ex vivo system used in a previous work was incubated in two separate containers, one for the testis and the other for the ganglion. Both organs remain interconnected (as in vivo) by the respective spermatic nerve. When noradrenaline was added to the inferior mesenteric ganglion, testosterone release in the gonad container underwent a progressive and significant increment. Propranolol diminishes and phentolamine increases the androgen release. When using the superior mesenteric ganglion, no changes were observed. These results indicate that the ganglionic stimulation of the autonomic system clearly participates in testosterone release from the testis. This effect depends on the ganglion involved. These results make it evident that not only the classical and well-known hypothalamus,hypophysial axis, but also the peripheral nervous system, via the autonomic ganglia, are directly involved in the endocrine control of the testis. [source]

Comparative efficacy of two ,1 -adrenoreceptor antagonists, doxazosin and alfuzosin, in patients with lower urinary tract symptoms from benign prostatic enlargement

BJU INTERNATIONAL, Issue 6 2004
T.M. De Reijke
OBJECTIVES To compare doxazosin and alfuzosin in patients with moderate to severe lower urinary tract symptoms (LUTS) suggestive of bladder outlet obstruction. PATIENTS AND METHODS In all, 210 men with LUTS were randomized to receive doxazosin 1,8 mg once daily or alfuzosin 5,10 mg divided in two or three daily doses in a 14-week, multicentre, double-blind, baseline-controlled, dose-titration study. The International Prostate Symptom Score (IPSS) and maximum urinary flow rate were used to assess the efficacy of the treatment. RESULTS At study completion, the mean dose of doxazosin was 6.1 mg/day and alfuzosin 8.8 mg/day. The least squares mean (se) change from baseline in total IPSS was ,9.23 (0.6) for doxazosin and ,7.45 (0.6) (both P < 0.001) for alfuzosin. The respective mean change from baseline in irritative symptoms was ,3.5 (0.2) and ,2.8 (0.3) (both P < 0.001). The differences between the treatment groups were statistically significant in favour of doxazosin (total IPSS, P = 0.036; irritative symptoms, P = 0.049). The improvement between groups was also significantly different for postvoid residual urine volume, at ,29.19 (8.6) and +,9.59 (8.9) mL for doxazosin and alfuzosin, respectively (P = 0.002). Improvements in mean and maximum urinary flow rates were similar for both treatments, at +,1.5 and +,1.2, and +,2.8 and +,2.5 mL/s, respectively. Doxazosin and alfuzosin were both well tolerated, with most all-cause adverse events reported as mild or moderate. CONCLUSIONS The mean doses of doxazosin and alfuzosin used in this study were not equipotent. Doxazosin 6.1 mg/day produced significantly greater improvements than alfuzosin 8.8 mg/day in total and irritative urinary symptom scores and postvoid residual urine volume in men with moderate to severe LUTS. Changes in maximum and mean flow rates were comparable. Doxazosin and alfuzosin were both well tolerated. [source]