Drugs online research references
Acta Physiol Scand. 1978 Jun;103(2):219-24.
The release of serotonin from rat duodenal enterochromaffin cells by adrenoceptor agonists studied in vitro.
Pettersson G, Dahlstrom A, Larsson I, Lundberg JM, Ahlman H, Kewenter J.
The serotonin (5-HT) content of enterochromaffin cells (EC) was studied by a cytofluorimetric method in biopsies from rat duodenal mucosa after in vitro incubation with different adrenoceptor agonists and antagonists and acetylcholine (ACh). Noradrenaline (NA), Adrenaline (A) and Isoprenaline (IP) caused a decrease of 5-HT in EC down to 40--60% and for NA and A this effect was concentration-dependent. The effect was antagonized by d,1-propranolol but not by d-propranolol, metoprolol, phentolamine or phenoxybenzamine indicating that the 5-HT release from EC is probably mediated via a true beta-adrenoceptor mechanism possibly of the beta2 type. ACh also decreased the 5-HT content of EC but was much less potent than the adrenergic substances. Dopamine (DA) had no effect.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=27945&dopt=Abstract
Circulation. 1999 Jul 27;100(4):346-53.
Effect of beta-blockers on free radical-induced cardiac contractile dysfunction.
Flesch M, Maack C, Cremers B, Baumer AT, Sudkamp M, Bohm M.
Klinik III fur Innere Medizin and Klinik fur Herz- und Thoraxchirurgie (M.S.) der Universitat zu Koln, Cologne, Germany.
BACKGROUND: We examined the effects of hydroxyl radicals (OH.) on human myocardial contractility and on sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) activity and the effects of the beta-receptor antagonists metoprolol, carvedilol, and its metabolite BM-910228. METHODS AND RESULTS: Isometric force of contraction was determined in isolated human myocardium. H(2)O(2) 1 mmol/L and Fe(3+)-nitrilotriacetic acid (Fe(3+)-NTA) 0.1 mmol/L used for generation of OH. induced a decrease in basal force of contraction and an increase in diastolic tension in atrial and left ventricular myocardial preparations. After challenge with OH., the maximum positive inotropic response to Ca(2+) 1.8 to 15 mmol/L was decreased by 60% and by 39%, respectively. The effects of OH. could be blocked by catalase. Carvedilol and its metabolite BM-910228 attenuated the OH.-induced impairment of the inotropic response to Ca(2+) in atrial myocardial preparations. Metoprolol had no significant effect. The stimulation frequency (0.5 to 3.0 Hz)-dependent increase in force of contraction and decrease in diastolic tension were abolished after exposure of atrial trabeculae to OH. In parallel, SERCA activity was decreased by OH. concentration-dependently, as determined in myocardial membrane preparations. BM-910228 partially restored the force-frequency relationship and preserved SERCA activity. CONCLUSIONS: OH. radicals induce an impairment of contraction and relaxation and an attenuation of the force-frequency relationship in human myocardium accompanied by an inhibition of SERCA. Carvedilol and BM-910228 partly prevented OH.-induced contractile dysfunction. These observations could explain the improvement of ejection fraction in heart failure trials with carvedilol without a restoration of beta-adrenergic receptor density.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10421593&dopt=Abstract
tin.it
BACKGROUND: Beta-blockers improve survival and ventricular function in patients with heart failure. We evaluated the long-term persistence of metoprolol-induced improvement and its impact on prognosis in idiopathic dilated cardiomyopathy. METHODS: Two hundred and four of 586 patients enrolled in a registry on the natural history of idiopathic dilated cardiomyopathy survived 4 years without transplantation; 98 of them were on standard heart failure treatment, whereas 106 took metoprolol in addition. We analyzed the effects of treatment using beta-blockers in terms of changes in left ventricular ejection fraction (LVEF), NYHA functional class and left ventricular end-diastolic diameter index (LVEDDI) after 1, 2 and 4 follow-up years in order to elaborate an improvement score that was related to the subsequent outcome over 60 months after the 4-year follow-up visit. RESULTS: Greater LVEF increases and NYHA functional class and LVEDDI decreases were observed in patients submitted to metoprolol vs standard treatment at all stages of follow-up. Changes (delta vs baseline) for LVEF (p = 0.02), NYHA functional class (p = 0.0001) and LVEDDI (p = 0.004) were maximal during the first year (10 +/- 11 vs 6 +/- 12 units, -0.72 +/- 0.77 vs -0.23 +/- 0.81, -3.5 +/- 5 vs -1.6 +/- 3.5 mm), persisted at 2 (12 +/- 12 vs 8 +/- 12 units, -0.80 +/- 0.70 vs -0.37 +/- 0.87, -4.2 +/- 5 vs -2.3 +/- 4 mm) but showed a trend to decline at 4 years (11 +/- 12 vs 8 +/- 13 units, -0.54 +/- 0.90 vs -0.24 +/- 0.91, -4.3 +/- 5 vs -2.3 +/- 5 mm) of follow-up. Improvement at 4 years was associated with a better transplant-free survival (81 vs 52%, p = 0.0005, odds ratio 0.36, 95% confidence interval 0.18 to 0.74). CONCLUSIONS: In idiopathic dilated cardiomyopathy, the more significant improvement in symptoms and left ventricular function and size, that is observed following treatment using metoprolol, translates into a better outcome. These benefits peak within the first 2 years of start of treatment but may begin to fade thereafter.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11256541&dopt=Abstract
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