title: Differential effects of timolol and metoprolol on platelet function at rest and during exercise.
abstract: Ten male patients suffering from stable angina pectoris were studied at rest and immediately after exercise during treatment either with timolol (a non-selective beta-blocker) or with metoprolol (a beta 1-selective blocker). Timolol induced a significant increase in platelet aggregation and a reduction in platelet cyclic AMP, and it also raised the plasma adrenaline at rest and during exercise as compared to the pre-treatment level. Metoprolol had none of these effects. Prior to medication and during metoprolol treatment, exercise led to an increase in the peripheral platelet count, whereas timolol was associated with a reduction of platelets during physical effort. Neither drug affected platelet thromboxane B2 at rest. During exercise, its level was not affected in the pre-treatment period or during metoprolol treatment but it was sharply increased by timolol therapy.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000188:drug therapy; D001792:Blood Platelets / Q000187:drug effects*; D004311:Double-Blind Method; D004837:Epinephrine / Q000097:blood; D005080:Exercise Test; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D005082:Physical Exertion; D010976:Platelet Count / Q000187:drug effects; D013999:Timolol / Q000494:pharmacology*
chemical_list: D000319:Adrenergic beta-Antagonists; D013999:Timolol; D008790:Metoprolol; D009638:Norepinephrine; D004837:Epinephrine