How is epinephrine reversal action of phenoxybenzamine?

All α-adrenergic blockers reverse the α-agonist actions of epinephrine. For example, the vasoconstrictive action of epinephrine is interrupted, but vasodilation of other vascular beds caused by stimulation of β receptors is not blocked Therefore, the systemic blood pressure decreases in response to epinephrine given in the presence of phenoxybenzamine