The present invention relates to an annular barrier to be expanded in an annulus between a well tubular metal structure and a wall of a borehole or another well tubular metal structure in a well in order to provide zone isolation between a first zone having a first pressure and a second zone having a second pressure of the borehole, the annular barrier comprising a tubular metal part adapted to be mounted as part of the well tubular metal structure, an expandable metal sleeve surrounding the tubular metal part, each end of the expandable metal sleeve being connected with the tubular metal part defining an annular space between the expandable metal sleeve and the tubular metal part. The annular barrier further comprises a valve unit having an initial position and an end position, the valve unit comprising a first aperture in fluid communication with the inside, a second aperture in fluid communication with the annular space, a third aperture in fluid communication with the annulus. The invention also relates to a downhole system comprising a well tubular metal structure and an annular barrier in which the tubular metal part of the annular barrier is mounted as part of the well tubular well tubular metal structure.