Effect of insulin on glucose oxidation and amino isobutyric acid transport and binding of insulin in chicken thymocytes.
In chicken thymocytes isolated from 15--40 day-old chickens, after a 2 h incubation at 37 degrees C, insulin stimulated amino isobutyric acid uptake (maximal response: 40--50% of increase at 1 microgram insulin/ml and half maximal response at 60 ng/ml) by specifically stimulating the influx without altering the efflux. Insulin also stimulated glucose oxidation (maximal response: 11% of increase at 1 microgram insulin/ml). Binding of 125I-labelled chicken insulin to thymocytes was rapid and higher at 15 degrees C than at 37 degrees C. At steady state, (90 min at 15 degrees C), chicken, porcine and goose insulins were equipotent in inhibiting the binding of 125I-labelled chicken insulin. Maximal binding capacity was estimated at 1250 pg insulin/10(8) cells, i.e., 1250 binding sites/cell with an apparent dissociation constant of 200 ng insulin/ml at 15 degrees C. Degradation of 125I-labelled chicken insulin in the incubation medium was negligible at 15 degrees C but very noticeable at 37 degrees C. Therefore, the low level of insulin binding at 15 degrees C reflects a true scarcity of insulin receptors in chicken thymocytes as compared to rat thymocytes.
D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002645:Chickens / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000502:physiology*; D010084:Oxidation-Reduction; D011972:Receptor, Insulin / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism*
D000621:Aminoisobutyric Acids; D007328:Insulin; D011972:Receptor, Insulin; D005947:Glucose