The interplay between supermassive black holes and their host galaxies Supermassive black holes reside in the hearts of almost all massive galaxies. Their evolutionary path seems to be strongly linked to the evolution of their host galaxies as implied by several empirical relations between the black hole mass (M BH ) and different host galaxy properties. The physical driver of this co evolution is however still not understood. More mass measurements over homogeneous samples and a detailed understanding of systematic uncertainties are required to fathom the origin of the scaling relations. In this thesis I present the mass estimations of supermassive black holes in the nuclei of one late type and thirteen early type galaxies. Our SMASHING sample extends from the intermediate to the massive galaxy mass regime and was selected to fill in gaps in number of galaxies along the scaling relations. All galaxies were observed at high spatial resolution making use of the adaptive optics mode of integral field unit (IFU) instruments on state of the art telescopes (SINFONI NIFS MUSE). I extracted the ...