Abstract
Peripheral muscle responsiveness to insulin was studied in neonatal rats in vivo by measuring incorporation of labelled glucose to glycogen in diaphragm. 14C glucose (4.2mM) was injected intraperitoneally (100 μl/10gm) with or without (control) insulin(570 mU/ml) into pups from 17 litters of Sprague Dawley rats by the Rafaelson technique. Diaphragms were excised after a 30-minute incubation at birth, 24, 48, 72, or 168 hrs. of age and in 12 adult rats. In control animals ml; by 72 hrs. of age, there was no significant difference in incorporation of labelled glucose. In insulin treated animals there was always an increased incorporation of labelled glucose in comparison to age-matched controls (p<.025). The insulin stimulated percent incorporation of labelled glucose was lower at birth (211%) and at 24 hrs. (235%), but increased with advancing age and approached adult levels by 168 hrs. (1815%). At birth and at 24 hrs. a 5 log insulin dose response curve showed significant incorporation only at 570 mU/ml; by 72 hrs. a significant increase was noted at 5.7 mU/ml insulin. Total muscle glycogen was high at birth (1.22gm%), fell to 50% of the birth value from 24 through 168 hrs., and would not account for the decreased insulin response noted. Preliminary studies of glucose transport using C deoxyglucose did not fully explain the reduced muscle response to insulin. Our data suggest a blunted responsiveness of muscle to insulin during the 1st 24 hrs.in rats probably related to attenuated intracellular response.
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Cowett, R., Czech, M., Susa, J. et al. 842 BLUNTED MUSCLE RESPONSIVENESS TO INSULIN IN THE NEONATAL RAT. Pediatr Res 12 (Suppl 4), 504 (1978). https://doi.org/10.1203/00006450-197804001-00847
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DOI: https://doi.org/10.1203/00006450-197804001-00847