Table 2.
Total hepatic blood flow, lactate, free fatty acid and glycerol metabolism, and nonhepatic glucose uptake before (−15 to 0 min) and during insulin-induced hypoglycemia (0-120 min)
| Group | Time, min |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Control period |
Hypoglycemic experimental period |
|||||||||
| −15 | 0 | 15 | 30 | 45 | 60 | 75 | 90 | 105 | 120 | |
| Total hepatic blood flow, mL/kg/min | ||||||||||
| NG | 27 ± 2 | 27 ± 2 | 32 ± 1 | 32 ± 2 | 38 ± 2 | 44 ± 2 | 45 ± 2 | 46 ± 1 | 47 ± 2 | 44 ± 1 |
| HG | 27 ± 2 | 27 ± 2 | 25 ± 2 | 28 ± 2 | 36 ± 4 | 40 ± 4 | 42 ± 3 | 41 ± 2 | 44 ± 3 | 41 ± 3 |
| HG-HeadEu | 26 ± 1 | 26 ± 1 | 29 ± 2 | 32 ± 2 | 34 ± 1 | 36 ± 3 | 38 ± 3 | 39 ± 3 | 40 ± 4 | 38 ± 3 |
| Arterial blood lactate, µmol/L | ||||||||||
| NG | 681 ± 97 | 723 ± 71 | 843 ± 94 | 979 ± 131 | 1,055 ± 159 | |||||
| HG | 637 ± 79 | 629 ± 118 | 851 ± 81 | 1,113 ± 180 | 1,277 ± 176 | |||||
| HG-HeadEu | 845 ± 57 | 940 ± 99 | 591 ± 36 | 580 ± 62† | 538 ± 80† | |||||
| Net hepatic lactate balance, µmol/kg/min | ||||||||||
| NG | 4.8 ± 1.8 | −0.1 ± 0.6 | −2.5 ± 0.9 | −2.3 ± 1.4 | −2.3 ± 1.3 | |||||
| HG | 6.0 ± 1.1 | 1.5 ± 1.2 | 4.8 ± 2.9* | −2.2 ± 1.6 | −1.7 ± 1.7 | |||||
| HG-HeadEu | 9.0 ± 1.5 | 3.0 ± 1.6 | 2.0 ± 1.4* | 2.8 ± 1.5 | 1.4 ± 1.3 | |||||
| Arterial plasma free fatty acids, µmol/L | ||||||||||
| NG | 417 ± 58 | 144 ± 38 | x405 ± 91 | 521 ± 126 | 404 ± 123 | |||||
| HG | 361 ± 77 | 107 ± 33 | 511 ± 100 | 405 ± 71 | 476 ± 71 | |||||
| HG-HeadEu | 386 ± 58 | 34 ± 15 | 104 ± 53† | 82 ± 24† | 102 ± 42† | |||||
| Net hepatic fee fatty acid balance, µmol/kg/min | ||||||||||
| NG | −1.4 ± 0.2 | −0.1 ± 0.3 | −3.1 ± 1.0 | −2.5 ± 0.9 | −1.5 ± 0.6 | |||||
| HG | −0.7 ± 0.3 | 0.2 ± 0.1 | −1.2 ± 0.4* | −1.0 ± 0.5* | −1.4 ± 0.6 | |||||
| HG-HeadEu | −1.4 ± 0.2 | −0.1 ± 0.3 | −0.7 ± 0.3* | −1.0 ± 0.5 | −0.7 ± 0.7 | |||||
| Arterial blood glycerol, µmol/L | ||||||||||
| NG | 50 ± 5 | 35 ± 6 | 119 ± 12 | 156 ± 19 | 156 ± 26 | |||||
| HG | 53 ± 3 | 45 ± 7 | 156 ± 14 | 192 ± 26 | 189 ± 29 | |||||
| HG-HeadEu | 67 ± 13 | 33 ± 5 | 62 ± 16† | 78 ± 15† | 83 ± 16† | |||||
| Net hepatic glycerol balance, µmol/kg/min | ||||||||||
| NG | −0.8 ± 0.1 | −0.9 ± 0.2 | −3.5 ± 0.4 | −4.6 ± 0.6 | −4.2 ± 1.1 | |||||
| HG | −0.9 ± 0.1 | −0.8 ± 0.2 | −4.1 ± 0.7 | −5.0 ± 0.7 | −4.9 ± 0.9 | |||||
| HG-HeadEu | −0.9 ± 0.2 | −0.5 ± 0.1 | −1.6 ± 0.6† | −2.3 ± 0.5† | −2.3 ± 0.7† | |||||
| Nonhepatic glucose uptake, mg/kg/min | ||||||||||
| NG | 2.5 ± 0.5 | 5.9 ± 0.8 | 7.5 ± 0.9 | 7.3 ± 0.7 | 7.6 ± 0.6 | 7.7 ± 0.6 | 7.2 ± 0.6 | |||
| HG | 2.5 ± 0.9 | 4.7 ± 1.3 | 6.2 ± 1.6 | 7.4 ± 1.2 | 6.4 ± 0.8 | 6.1 ± 1.3 | 5.7 ± 1.1 | |||
| HG-HeadEu | 1.9 ± 0.3 | 8.9 ± 1.0† | 8.8 ± 0.7 | 9.0 ± 0.6 | 9.9 ± 0.7 | 9.5 ± 0.5 | 10.3 ± 0.9† | |||
Positive and negative values for net hepatic substrate balances indicate production and uptake, respectively. HG, intraportal (Po) infusion of fructose was used to stimulate hepatic glucose uptake; NG, saline was infused Po to maintain liver glycogen levels close to a normal, fasting level; HG-HeadEu, subset of HG group in which brain euglycemia was maintained by infusing glucose bilaterally into the carotid and vertebral arteries. *P < 0.05, compared with NG. †P < 0.01, compared with NG and HG.