tokens: Both the pressor and bradycardia effects of cirazoline were abolished in chronic prazosin treated SHR ( n = 4 ) as compared to the untreated SHR ( n = 4 ). On the other hand , the pressor effects of Abbott-53693 were similar in both groups of SHR , but the accompanying bradycardia was greater in SHR with chronic prazosin treatment than without such treatment .