Changes in rates of glucose utilization and regulation of glucose disposal by fast-twitch skeletal muscles in late pregnancy.
Glucose utilization indices (GUI) were measured in vivo in conjunction with active pyruvate dehydrogenase complex (PDH(a) and glycogen synthase (GS) activities in fast-twitch skeletal muscles [extensor digitorum longus (EDL), tibialis anterior and gastrocnemius] of late-pregnant rats and age-matched virgin control rats in the fed state, after 24 h starvation and at 2 h after re-feeding with standard laboratory chow ad libitum after 24 h starvation. As demonstrated previously [Holness and Sugden (1990) Biochem. J 277, 429-433], GUI values of fast-twitch skeletal muscles of virgin rats were low in the fed ad libitum and the 24 h-starved states, but dramatically increased after subsequent chow re-feeding. GUI values of fast-twitch skeletal muscles of late-pregnant rats were also low in the fed and starved states and were increased by re-feeding, but the increase in GUI values elicited by re-feeding was greatly attenuated. PDHa activities in EDL, tibialis anterior and gastrocnemius in the fed state were unaffected by late pregnancy, and skeletal-muscle PDHa activities were decreased after 24 h of starvation in both groups. Whereas re-feeding of virgin rats with standard diet for 2 h restored PDHa activities in fast-twitch skeletal muscles to values for rats continuously fed ad libitum, PDHa activities in fast-twitch skeletal muscles of late-pregnant rats, although increased in response to re-feeding, remained considerably less than the corresponding fed ad libitum values after 2 h of re-feeding. In contrast, neither skeletal-muscle GS re-activation nor rates of skeletal-muscle glycogen deposition after re-feeding were markedly affected by late pregnancy. The results are discussed in relation to the specific targeting of individual pathways of glucose disposal in fast-twitch skeletal muscles during re-feeding in late pregnancy.
Department of Biochemistry, Faculty of Basic Medical Sciences, Queen Mary and Westfield College, University of London, U.K.
M J
MJ
Holness
M C
MC
Sugden
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005502:Food; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007657:Ketone Bodies / Q000097:blood; D009132:Muscles / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013217:Starvation
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007657:Ketone Bodies; D011768:Pyruvate Dehydrogenase Complex; D006003:Glycogen; D006006:Glycogen Synthase; D005947:Glucose