In AD 545 Pope Vigilius was on his way to Constantinople. According to the Liber Pontificalis, he was effectively under arrest because of his reluctance to condemn the Three Chapters. Ampliatus must have been one of the clerics who accompanied him. When on Sicily, Vigilius realised that he might be out of Rome for a long time (in fact he never returned there until his death ten years later), so he sent Ampliatus together with bishop Valentine to act in his place. We know that Ampliatus was performing such tasks in the 550s (Pelagius I, Ep. 14, XXXXXX). One must remember, however, the role played in the church of Rome by the presbyter Mareas  at the same time.