The neutrino synchrotron radiation for a completely relativistic electron gas in the presence of large magnetic field is computed according to the photon neutrino coupling theory of weak interactions. The radiation is also estimated for the non-relativistic case. The neutrino luminosity of several model white dwarfs are computed according to the photon-neutrino coupling theory and compared with that of the current-current coupling theory. It is shown that, according to the photonneutrino coupling theory, the neutrino luminosity is greater than the photon luminosity and, therefore, most likely to have astrophysical significance in the evolution of stars with large electron energies and potentially large magnetic field, such as white dwarfs.