STUDIES ON THE TUMOR-PROMOTING ACTIVITY OF POLYURETHANES - DEPLETION OF INHIBITORY-ACTION OF METABOLIC COOPERATION ON THE SURFACE OF A POLYALKYLENEURETHANE BUT NOT A POLYETHERURETHANE

Methanol extracts prepared from three polyetherurethanes (PEUs), namel y PU4, PU6, and PU8, which were synthesized using 4,4'-diphenylmethane diisocyanate, poly(tetramethylene oxide), and 1,4-butanediol, showed a n inhibitory action on the gap-junctional intercellular communication in a V79 metabolic cooperation (MC) test system. However, the inhibito ry potentials of methanol extracts did not correlate with the tumorige nic potential of the polyurethanes in 1-year rat implantation studies. When the MC test was carried out using glass dishes partly coated wit h low molecular weight PEU, the inhibitory activity was clearly detect ed on the surface of the polyurethane coating but not on that of the n oncoated glass area. The inhibitory activity of the three PEUs investi gated using polyurethane-coated dishes correlated with the values of t he polyurethane's tumorigenic potential in the rat implantation study. Various polyurethanes containing polybutadiene (PBD), hydrogenated po lybutadiene (HPBD), or a fluoropolyether glycol (FPEG) as the soft seg ment were also tested using coated dishes in the MC assay. The thresho ld inhibitory response of FPEG-PU was 10-fold less than that of PU4, a nd neither PBD-PU nor HPBD-PU showed any inhibition in the MC test sys tem. Both the FPEG and aliphatic soft segment containing polyurethanes decreased, and had minimal influence on the gap junctional intercellu lar communication. Thus, the tumor-promoting potential of PBD-PU, HPBD -PU, and SPEG-PU was considered to be lower than those of the PEUs bas ed on these in vitro test results. (C) 1995 John Wiley and Son's, Inc.