The acute metabolic effects of glucagon and its interactions with insulin in forearm tissue

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Abstract
The acute effects of glucagon (mol. wt. 3500) and its interactions with insulin were studied in the forearm during eight studies in seven normal, post-absorptive males. The protocol consisted of a 2 h baseline, 1 h glucagon perfusion (mean glucagon increment, 691±50 pg/ml), 1 h perfusion of both insulin and glucagon (mean insulin increment of 105 ±13 mU/l) and a 30 min recovery period. Simultaneous arterial (A), deep venous (DV), and superficial venous (SV) blood samples were obtained at 30 min intervals. Perfusion of glucagon resulted in a decrease in (A-DV) non-esterified fatty acids of-0.128±0.057 mmol/l (n=7, p<0.05) and (A-SV) non-esterified fatty acids of -0.081±0.036 mmol/l (n=7, p<0.05), as well as a change in deep compartment uptake of glycerol after 60 min of -0.044±0.019 μmol/min/100 ml of forearm tissue (n=6, p<0.05), indicating increased lipolysis. There was also a decrease in net glucose uptake as reflected by a change in (A-DV) of -0.24±0.09 mmol/l (n=7, p<0.025) and (A-SV) of 0.10± 0.05 mmol/l (n=7, p<0.05). There was also a net decrease in deep arteriovenous differences of potassium in six of seven subjects. Insulin levels, similar to those found after a meal, rapidly reversed the effects of glucagon on non-esterified fatty acid, glucose and potassium. These effects persisted throughout the recovery period.