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

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 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 less than 0.05) and (A-SV) non-esterified fatty acids of -0.081 +/- 0.36 mol/l (n = 7, p less than 0.05), as well as a change in deep compartment uptake of glycerol after 60 min of -0.044 +/- 0.019 mumol/min/100 ml of forearm tissue (n=6, p less than 0.05), indicating increased lipolysis. There was also a decrease in net glucose uptake as reflected by a change in (A-Dids of -0.081 +/- 0.36 mol/l (n = 7, p less than 0.05), as well as a change in deep compartment uptake of glycerol after 60 min of -0.044 +/- 0.019 mumol/min/100 ml of forearm tissue (n=6, p less than 0.05), indicating increased lipolysis. There was also a decrease in net glucose uptake as reflected by a change in (A-Dids of -0.081 +/- 0.36 mol/l (n = 7, p less than 0.05), as well as a change in deep compartment uptake of glycerol after 60 min of -0.044 +/- 0.019 mumol/min/100 ml of forearm tissue (n=6, p less than 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 less than 0.025) and (A-SV) of 0.10 +/- 0.05 mmol/l (n = 7, p less than 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.