The influence of collisional excitation mechanisms on the spectral line shape of an atom in an external electric field is investigated theoretically. The formation of line profiles is studied in the density matrix representation for 4 1S0 - 2 1P1, 4 1P1 - 2 1S0, 4 1D2 - 2 1P1, 4 3S1 - 2 3P0,1,2, 4 3P0,1,2 - 2 3S1 transitions of the He atom excited by the electron impact in an external electric field.