We present high resolution H \alpha rotation curves of 4 late-type dwarf galaxies and 2 low surface brightness galaxies ( LSB ) for which accurate HI rotation curves are available from the literature .
Observations are carried out at Telescopio Nazionale Galileo ( TNG ) .
For LSB F583-1 an innovative dispersing element was used , the Volume Phase Holographic ( VPH ) with a dispersion of about 0.35 Åpxl ^ { -1 } .

We find good agreement between the H \alpha data and the HI observations and conclude that the HI data for these galaxies suffer very little from beam smearing .
We show that the optical rotation curves of these dark matter dominated galaxies are best fitted by the Burkert profile .
In the centers of galaxies , where the N-body simulations predict cuspy cores and fast rising rotation curves , our data seem to be in better agreement with the presence of soft cores .