heterologous desensitization (also known as cross-desensitization) is the term for the unresponsiveness of cells to one or more agonists to which they are normally responsive. typically, desensitization is a receptor (biochemistry)-based phenomenon in which one receptor type, when bound to its ligand, becomes unable to further influence the signalling pathways by which it regulates cells and, in the case of cell surface membrane receptors, may thereafter be internalized. the desensitized receptor is degraded or freed of its activating ligand and re-cycled to a state where it is again able to respond to cognate ligands by activating its signalling pathways.