Inhibitory effect of anoxia on 125I-insulin binding by rat hepatocytes.
We have examined the possibility that 125I-insulin binding by isolated rat hepatocytes is modulated by cellular ATP levels. To avoid complications due to ATP-dependent internalization of bound insulin, 125I-insulin binding was determined at 10 degrees C; at this temperature, equilibrium binding was achieved after incubation for 4-6 h. When hepatocytes were incubated at 37 degrees C under anaerobic conditions, ATP levels and 125I-insulin binding were both lowered by about 65%. Anoxia inhibited the association of 125I-insulin with the hepatocyte receptor; the dissociation of insulin from hepatocytes was not affected. Cellular ATP levels and 125I-insulin binding were both restored when anaerobic cells were incubated further at 37 degrees C under aerobic conditions. When anaerobic cells were incubated in air at 10 degrees C during the insulin binding assay, 125I-insulin binding recovered completely, but ATP levels were unaffected. The inhibitory effect of anoxia on 125I-insulin binding was not due to any effect on 125I-insulin degradation or on cell viability. We conclude (1) that the ability of hepatocytes to bind insulin can be modulated on a short-term basis in response to the metabolic status of the cell, and (2) that modulation of the liver cell insulin receptor is not a function of cellular ATP levels.
D000693:Anaerobiosis; D000818:Animals; D005260:Female; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008099:Liver / Q000378:metabolism*; D010100:Oxygen / Q000502:physiology*; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism
D007328:Insulin; D007457:Iodine Radioisotopes; D011972:Receptor, Insulin; D010100:Oxygen