Relation of the velocity dispersion and ¹²CO(J = 1 − 0) luminosity surface density. Different galaxies are marked in different colors as shown in the legend. The orthogonal distance regression fittings for different galaxies are displayed as straight lines in different colors. The solid pink circles and the solid pink line of NGC 1365 show the data and the fitting result from the arm region, respectively, and the solid pink triangles and the dashed pink line display the data and the fitting result from the bar region, respectively. The solid orange circles and the solid orange line of NGC 3627 show the data and the fitting result from the arm region, respectively, and the solid orange triangles and the dashed orange line display the data and the fitting result from the bar region, respectively.