A phenomenological model is proposed for the transformation of interband conductivity caused by electron transitions through the optical (dielectric) gapℏ&ohgr;ginto the intraband conductivity of hole carriers in high-temperature superconductors under chemical doping. The interrelation between the interband and intraband conductivity components is analyzed in terms of the spectral functionN(&ohgr;)∼∫&sgr;(&ohgr;)d&ohgr;for integral conductivity of the normal phase. Two groups of coexisting charge carries of thep- andd-types with different relations with interband transitions are singled out. The integral conductivity of narrow-bandd-carriers is determined by interband excitations with the gap attenuation&Ggr;∝&ohgr;g.The integral conductivity of wide-bandp-carriers is not connected with interband excitations and is determined by the standard Drude spectrum. The obtained spectral functions are compared with the available data forLa2−xSrxCuO4andYBa2Cu3O6+xin the doping range from the beginning of metallization up to loss of superconductivity. The good agreement with the experimental data leads to the following conclusions: (i) the integral interband conductivity at the doping stage with increasing temperature of superconducting transition is mainly determined by thed-component to which interband excitations are “pumped;” (ii) as soon as one of the planesCuO2orCuOxgoes over to a predominantlyp-metal state, a noncorrelated metal with loss of superconductivity is formed. ©1998 American Institute of Physics.