Adrenergic responsiveness after abrupt propranolol withdrawal in normal subjects and in patients with angina pectoris.

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Abstract
Adrenergic responsiveness after abrupt propranolol withdrawas during exogenous and esdogenous catecholamine stimulation was assessed in 10 normal subjects and 10 patients with angina pectoris. Propranolol, 160 mg/day, was administered for 2 weeks and then stopped. During an epinephrine infusion, period (p < 0.005). There were no differences from control 96 hours after the drug had been stopped in both groups or at 144 hours in the angina patients who were studied for a longer time. At 48 hours of heart rate and the pressure-rate product were significantly less than control level in the angina patient, but not in the normal subjects. Similar results were observed during exercise in both groups. The epinephrine-induced increase in free fatty acids was blocked by propranolol (p < 0.005), was still attenuated at 48 hours of withdrawals (p < 0.05), but returned to control levels thereafter in both groups. Resting serum triiodothyromine levels decreased with propranolol ( < 0.005) and remaind low throughout the withdrawal period. Measurements of dopamine beta-hydroxylase, plasma platelet factor 4, and platelet aggregation at rest and after exercise did not change significantly during or after propranolol administration. Plasma norepinephrine and epinephrine values were not changed from control during the withdrawal period at rest or after exerise. We conclude that there is no evidence of hypersensitivity to beta-adrenergically mediated responses after abrupt propranolol withdrawal.