True about beta blockers all except:

Ref: Goodman and Gilman's "Pharmacological Basis of Therapeutics " 12th edExplanation:Beta blockers do not commonly cause postural hypotension.Postural hypotension is commonly seen with alpha blockers.Alpha-receptor antagonists often cause orthostatic hypotension and reflex tachycardia.Orthostatic hypotension is due to antagonism of sympathetic nervous system stimulation of a 1 receptors in vascular smooth muscle.Contraction of veins is an important component of the normal capacity to maintain blood pressure in the upright position since it decreases venous pooling in the periphery.Tachycardia may be more marked with agents that block a 2presynaptic receptors in the heart, since the augmented release of norepinephrine will further stimulate a receptors in the heart.Beta blocker side effectsBradycardia is a normal response to beta receptor blockade; however, in patients with partial or complete AV conduction defects, beta antagonists may cause life-threatening bradyarrhyth mias.Symptoms of peripheral vascular disease may worsen, although this is uncommon, or Raynaud's phenomenon may develop.The number of receptors on circulating lymphocytes is increased in subjects who have received propranolol for long periods; pindolol has the opposite effect.CNS side effects may include fatigue, sleep disturbances (including insomnia and nightmares), and depression and is related to lipophilicity.Glucagon is the drug of choice for beta blocker overdoseBeta Receptor antagonists block catecholamine- induced tremor.They also block inhibition of mast-cell degranulation by catecholamines.