Glucose Transport in Human Skeletal Muscle: The In Vivo Response to Insulin (original) (raw)

Transmembrane glucose transport plays a key role in determining insulin sensitivity. We have measured in vivo WBGU, FGU, and K ln and K out of 3-O-methyl-D-glucose in forearm skeletal muscle by combining the euglycemic clamp technique, the forearm-balance technique, and a novel dual-tracer (1-[ 3 H]-L-glucose and 3-O-[ 14 C]-methyl-D-glucose) technique for measuring in vivo transmembrane transport. Twenty-seven healthy, lean subjects were studied. During saline infusion, insulin concentration, FGU (n = 6), K ln , and K out (n = 4) were similar to baseline. During SRIF-induced hypoinsulinemia (insulin <15 pM, n = 4) WBGU was close to 0, and FGU, K ln , and K out were unchanged from basal (insulin = 48 pM) values. During insulin clamps at plasma insulin levels of-1 8 0 (n = 4),-4 2 0 (n = 5),-3000 (n = 4), and-9500 pM (n = 4), WBGU was 14.2 ± 1.3, 34.2 ± 4.1 (P < 0.05 vs. previous step), 55.8 ± 1.8 (P < 0.05 vs. previous step), and 56.1 ± 6.3 ixmol • min~1 • kg" 1 of body weight (NS vs. previous step), respectively. Graded hyperinsulinemia concomitantly increased FGU from a basal value of 4.7 ± 0.5 jimol • rnin" 1 • kg" 1 up to 10.9 ± 2.3 (P < 0.05 vs. basal value), 26.6 ± 4.5 (P < 0.05 vs. previous step), 54.8 ± 4.3 (P < 0.05 vs. previous step), and 61.1 ± 10.8 junol • min" 1 • kg" 1 of forearm tissues (NS vs. previous step), respectively. K ln of 3-O-methyl-D-glucose in forearm skeletal muscle was increased by hyperinsulinemia from a basal value of 6.6 • 10" 2 ± 0.38 • 10" 2 to 10.0 • 10" 2 ± 1.4 • 10" 2