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Related to beta-blockers: alpha-blockers


A class of medication used to block the cellular response to chemicals normally present in the body.


; beta-adrenoceptor-blocking drugs; ß-blockers agents that block beta- adrenoceptors of heart, peripheral vasculature, bronchi, pancreas and liver; often administered in conjunction with thiazide diruetics; cardiovascular effects: slow heart rate, reduce blood pressure; relieve symptoms of glaucoma; exacerbate Raynaud's; bronchial effects: exacerbate asthma; pancreatic effects: tend to impaired glucose tolerance and mask early symptoms of hypoglycaemia; hepatic effects: additive toxic effect with local anaesthetic (see also Table 1)
Table 1: Effects of stimulation of alpha, beta and dopamine receptors
ReceptorActionStimulating drug
Alpha-1 (a1); postsynapticVasoconstriction; positive inotropism; antidiuresisAdrenaline +
Noradrenaline +++
Alpha-2 (a2); presynapticVasodilatation; inhibition of noradrenaline releaseAdrenaline +
Noradrenaline +++
Dopamine +
Alpha-2 (a2); postsynapticConstriction of coronary arteries; promotion of salt and water excretionAdrenaline +
Noradrenaline +++
Dopamine +
Beta-1 (ß1); postsynapticPositive inotropism; chronotropism; renin releaseAdrenaline ++
Noradrenaline ++
Isoprenaline ++
Dopamine +
Beta-2 (ß2); presynapticNoradrenaline release accelerated; positive inotropism; chronotropismAdrenaline +
Isoprenaline +++
Beta-2 (ß2); postsynapticVasodilatation; relaxation of bronchial smooth muscleAdrenaline +
Isoprenaline +++
Dopamine1; postsynapticVasodilatation; diuresisDopamine ++
Dopamine1; presynapticInhibits noradrenaline releaseDopamine +

Plus signs indicate degree of effect.

References in periodicals archive ?
Patients with diabetes must be warned that beta-blockers may suppress the warning signs of low blood sugar.
TABLE How metoprolol succinate vs placebo compares with other beta-blockers vs placebo (2) Comparison Randomized controlled trials RRR * Bisoprolol CIBIS-II (N=2647; 95% Cl,19-46; P<.
This meta-meta-analysis also included three meta-analyses of comparative trials of beta-blockers versus diuretics and three meta-analyses of beta-blockers compared with other drugs.
We chose to study effective beta-blockade rather than just administration of beta-blockers, because we assumed that a strongly positive result would encourage careful titration of beta-blockers perioperatively.
The major limitation of this work is that we only know what happens when you add beta-blockers to thiazides and calcium channel blockers.
Researchers found that beta-blocker use was not associated with depression in a case-control study examining 4,302 New Jersey Medicaid records.
Patients on beta-blockers were significantly older (51 years vs.
The diabetogenic potential of thiazide-type diuretic and beta-blocker combinations in patients with hypertension.
Nice said the decision not to recommend beta-blockers for first-line therapy was based on evidence that suggested they performed less well than other drugs ( particularly in the elderly.
Reader: My cardiologist has me taking a beta-blocker, atenolol, for high blood pressure.