Natural Gas Line question

My kitchen has an island that has an Electric downdraft stove top. I would like to replace it with a Gas stove top. But there is no gas line to the island.
The house is built on a slab (McKinney, Texas)

Here is what I was thinking of having done.

Install a ventilation hood over the island and then have a gas contractor run flexible gas line through the existing ventilation line to the island.
The existing ventilation line goes from the electric stove top's downdraft fan through the cabinet and under the slab to an exhaust vent on the outside of the house (right below the kitchen window). The total run of this ventilation line is about 10 feet.

Would it be possible to run a flexible gas line(Gastite) through the ventilation line?

Thanks,
Mike

So, the ventilation line you would be using, is the old discontinued one?
If that is the case, it should be okay to run the gas line there.

You could also check with the local inspector just to be sure.

Right.
I will be installing a new ventilation hood over the island.
The existing electric stove has a downdraft fan.
My new gas stove will not be a downdraft version.
I was hopeing to use the ventilation line that goes from the island to the outside of the house (under the slab) for the gas line.
I can run a new ventilation line from the ventilation hood to the outside through the ceiling.

Thanks,

Mike