The reactivation process of a muon that is stuck to an alpha-particle produced in muon-catalyzed deuterium-tritium (D-T) fusion is studied for the different isotope targets p, d, and t by using the Born approximation calculation of charge-transfer cross sections. The isotope dependence is small compared with the large isotope effects observed by Jones et al. Our calculated density dependence is very similar to that of Bracci and Fiorentini, and it is not as large as that observed by Jones et al. The enhancement of muon reactivation by application of a high-intensity electric field to the target is studied. Even when the very high electrical field of 40 MV/cm is applied to a liquid-hydrogen target, the enhancement is small because of the isotropic emission of an alpha particle in unpolarized D-T fusion. Even in polarized D-T fusion, the enhancement is small.