Insulin does not stimulate β-alanine transport into human skeletal muscle

LS Goncalves, C Kratz, L Santos… - … of Physiology-Cell …, 2020 - journals.physiology.org
LS Goncalves, C Kratz, L Santos, VH Carvalho, LP Sales, K Nemezio, I Longobardi
American Journal of Physiology-Cell Physiology, 2020journals.physiology.org
To test whether high circulating insulin concentrations influence the transport of β-alanine
into skeletal muscle at either saturating or subsaturating β-alanine concentrations, we
conducted two experiments whereby β-alanine and insulin concentrations were controlled.
In experiment 1, 12 men received supraphysiological amounts of β-alanine intravenously
(0.11 g· kg− 1· min− 1 for 150 min), with or without insulin infusion. β-Alanine and carnosine
were measured in muscle before and 30 min after infusion. Blood samples were taken …
To test whether high circulating insulin concentrations influence the transport of β-alanine into skeletal muscle at either saturating or subsaturating β-alanine concentrations, we conducted two experiments whereby β-alanine and insulin concentrations were controlled. In experiment 1, 12 men received supraphysiological amounts of β-alanine intravenously (0.11 g·kg−1·min−1 for 150 min), with or without insulin infusion. β-Alanine and carnosine were measured in muscle before and 30 min after infusion. Blood samples were taken throughout the infusion protocol for plasma insulin and β-alanine analyses. β-Alanine content in 24-h urine was assessed. In experiment 2, six men ingested typical doses of β-alanine (10 mg/kg) before insulin infusion or no infusion. β-Alanine was assessed in muscle before and 120 min following ingestion. In experiment 1, no differences between conditions were shown for plasma β-alanine, muscle β-alanine, muscle carnosine and urinary β-alanine concentrations (all P > 0.05). In experiment 2, no differences between conditions were shown for plasma β-alanine or muscle β-alanine concentrations (all P > 0.05). Hyperinsulinemia did not increase β-alanine uptake by skeletal muscle cells, neither when substrate concentrations exceed the Vmax of β-alanine transporter TauT nor when it was below saturation. These results suggest that increasing insulin concentration is not necessary to maximize β-alanine transport into muscle following β-alanine intake.
American Physiological Society
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