In late pregnancy insulin-dependent glucose transport/phosphorylation is selectively impaired and activation of glycogen synthase by insulin facilitated in skeletal muscles of 24-h starved rats

Abstract

Glucose sparing during pregnancy is achieved through suppression of glucose utilisation by the skeletal muscle mass [1±4]. This adaptation spares glucose for use by the feto-placental unit by limiting maternal glucose utilisation [2,3,5] and is also an important adaptation for safeguarding fetal nutrient supply during periods of nutrient (e. g. glucose) scarcity. Individual skeletal muscle types respond selectively to the requirement for glucose sparing during pregnancy [1]. Although suppression of glucose utilisation is more pronounced in slow-twitch (oxidative) skeletal Diabetologia (1999) Abstract Aims/hypothesis. We investigated the relation between glucose transport/phosphorylation and glycogen synthase activation in individual rat skeletal muscles in response to moderate hyperinsulinaemia in the absence or presence of hyperglycaemia during pregnancy. Methods. Rats were studied on day 20 of pregnancy after 24-h starvation, with unmated rats as controls. Insulin and glucose were infused into conscious rats through an indwelling cannula as specified. Glucose transport/phosphorylation was assessed in vivo using 2-deoxy-[1-3

Decreased contraction-stimulated glucose transport in isolated epitrochlearis muscles of pregnant rats

“…Accord- ingly, we assessed glycogen levels and found that pregnancy was associated with a nonsignificant trend for 13% increase in resting glycogen concentrations in epitrochlearis muscles, a result similar to the data of Holness and Sugden (17,18). Our results also indicated that pregnancy did not alter the amount of contraction-induced glycogen depletion.…”

“…Results from several studies suggest that late pregnancy may increase skeletal muscle resting glycogen concentrations (17,18,28), and previous studies have implicated precontraction glycogen concentration as a regulator of contraction-induced glycogen depletion and glucose transport (15,22,23). Accord- ingly, we assessed glycogen levels and found that pregnancy was associated with a nonsignificant trend for 13% increase in resting glycogen concentrations in epitrochlearis muscles, a result similar to the data of Holness and Sugden (17,18).…”

“…In this study, isolated epitrochlearis muscles from pregnant and nonpregnant rats were stimulated to contract by the same stimulation protocol. In addition, insulin-stimulated glucose uptake was determined for epitrochlearis muscles so that the magnitude of pregnancy effects on the two major pathways for activating muscle glucose transport could be compared in the same study.Under resting conditions, skeletal muscle glycogen concentration is similar or higher for pregnant compared with nonpregnant rats (17,18,28). However, the effect of contractile activity on glycogen depletion during pregnancy has apparently not been previously reported.…”

“…Under resting conditions, skeletal muscle glycogen concentration is similar or higher for pregnant compared with nonpregnant rats (17,18,28). However, the effect of contractile activity on glycogen depletion during pregnancy has apparently not been previously reported.…”

Correlação entre cálcio e insulina durante o teste de tolerância à glicose em ovelhas gestantes e não gestantes

“…Alguns autores têm correlacionado a manifestação dessa enfermidade com o balanço energético em ruminantes (Schlumbohm et al, 2003;Ingvartsen, 2006), e mesmo na década de 70, já havia sido demonstrada em vacas leiteiras a relação da concentração de cálcio na diminuição da secreção de insulina (Blum et al, 1972). Recentemente essas relações foram mais bem exploradas, demonstrando a participação do cálcio nas diferentes fases de secreção de insulina pelas células β-pancreáticas (Walz, 2007) e no metabolismo de carboidratos (Schlumbohm et al, 2003;Rutter et al, 2006).…”