  The heavy singlet field is integrated out from the U_L(3) x U_R(3) Chiral
Perturbation Theory and it is shown how its effects on the low-energy dynamics
are reduced to effective vertices for the light mesons. The results are matched
against the standard SU_L(3) x SU_R(3) Chiral Perturbation Theory in order to
establish the relations between the coupling constants from both theories to
one-loop level accuracy.
