Beta-blockade antagonism of tyramine-induced rise in blood pressure.

The effect beta-adrenoceptor blockade on the pressor response to tyramine has been investigated in 6 healthy volunteers, each submitted to an i.v. tyramine pressor test before and after 7 days of propranolol 40 mg b.d. or indenolol 60 mg o.d. Tyramine was given as i.v. boluses of 1-6 mg, alternating with saline, in a randomized, single blind fashion. Prior to treatment tyramine caused a temporary, dose-dependent increase in systolic and diastolic blood pressure, whilst the heart rate remained unaffected. Both propranolol and indenolol reduced the pressor response to tyramine, as shown by a significant increase in ED15, i.e. the dose of tyramine required to increase systolic blood pressure by 15%.