THE DIABETIC STATE INCREASES THE ACTIVITY BUT NOT THE NUMBER OF PERITONEAL-MACROPHAGES IN THE GK RAT PROMOTING THE TUBE FORMATION OF CULTURED ENDOTHELIAL-CELLS IN RAT AORTA

The influence of the diabetic state on the number and activity of intr aperitoneal macrophages was investigated in the GK rat. This rat is a model of non-insulin-dependent diabetes mellitus and was established f rom the normal Wistar rat. The cell number of a macrophages preparatio n in diabetic GK rats (10-15 weeks of age) did not differ from that in normal Wistar rats (9-10 weeks of age). The co-cultured macrophages i n diabetic GK rats (9-12 weeks of age) significantly increased the tub e formation of aortic endothelial cells (EC) compared with that in age -matched Wistar rats. The conditioned medium obtained from a culture o f macrophages from GK rats also increased tube formation more than tha t from a culture of macrophages from Wistar rats. The effect of macrop hages in the GK rat was not influenced by interferon-gamma (160 and 46 0 phr), but macrophages in normal rats were activated by these concent rations of interferon-gamma. In conclusion, the diabetic state increas ed the activity but not the number of macrophages in the GK rat, to st imulate tube formation of EC. The tube-forming effect of macrophages i n the diabetic state may depend on released factors which differ from that of normal macrophages.