In this dissertation, we study the scale of function spaces Mp(Rn) introduced by Zamboni. For these spaces, we get a characterization in terms of nonlinear Bessel potentials. This result is based on a known characterization of the Kato class Kn,s of order s in terms of Bessel potentials. We also introduce and study new function classes Ppn,T([0,T] x Rn) and Apn,T([0,T] x Rn) these classes generalize the classes Pn,T([0,T] x Rn) and An,T([0,T] x Rn) introduced by Gulisashvili.