  The simple model describing charge independence and charge symmetry breaking
of the pion-nucleon coupling constant is proposed. The model, which has simple
physical meaning and foundation, suggests directly proportional dependence of
the pion-nucleon coupling constants on the masses of interacting nucleons and
pions. Charge dependence of the pion-nucleon coupling constant and the
$^{1}S_{0}$-state low-energy nucleon-nucleon ($NN$) scattering parameters are
studied on the basis of the Yukawa meson theory. The values of the $np$ and
$nn$ interaction characteristics calculated by the proposed model agree quite
well with the experimental data.
