Polyamines are found in every cell of the body and the intricate enzymatic reactions responsible for their metabolism and transport in mammalian cells are now well understood. Despite intense efforts, elucidation of the role of polyamines has suffered in that little information of physiological relevance has surfaced. Recently, recombinant receptor techniques and increased availability of polyamine analogues have revealed, as discussed here by David Johnson, modulation of NMDA receptors by polyamines by reversal of tonic proton inhibition, and a function for these compounds as 'intrinsic rectifier factors' for K+ channels.