It is noted that Debye shielding between charges in a one-fluid plasma, and under certain conditions in a two-fluid plasma, can be represented formally by coupling the charges to a field of isothermal plasma oscillations. The field-theoretic calculation required in such a model would be equivalent mathematically to the coupling of point sources to a field having quanta of nonzero mass, and so the resulting potentials would have the same form, as is known to be the case in the usual thermodynamic model for Debye shielding.