  New CO(1-0) and CO(2-1) profiles complemented by data from the literature are
used to obtain CO linewidths for 29 barred spiral galaxies with young nuclear
starbursts. The ages of the starbursts were estimated from optical spectroscopy
and recent evolutionary synthesis models. The CO linewidths and the starburst
ages are correlated : galaxies with young (4-6 Myr) starbursts display narrow
(< 100 km/s) CO line while those with older starbursts show broader CO lines.
We discuss several scenarios of the gas dynamics during the nuclear starbursts'
evolution to interpret the correlation.
