Secretory Response of Glucagon to Hemorrhage

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Abstract
Glucagon was implicated in the hormonal-metabolic response to injury and in the restitution of blood volume. Evidence for this was obtained largely from observations of peripheral glucagon concentrations. The secretory response to mild or moderate hemorrhage remains undefined. Experiments were conducted in conscious dogs surgically prepared with indwelling catheters in the portal vein (PV), femoral artery (FA) and femoral vein (FV). In addition, electromagnetic flow probes were placed about the PV and the hepatic artery (HA). Animals were subsequently subjected to a 10% (7.5 ml/kg), 20% (15 ml/kg) or 30% (22.5 ml/kg) 3-min hemorrhage. The portal venous delivery rate (PVDR) of immunoreactive plasma glucagon (IRG), portal venous IRG concentration (PVIRG), and peripheral arterial IRG (AIRG) demonstrated variable changes following hemorrhage. When hemorrhage resulted in marked deterioration in PVBF [blood flow], the PVDR did not correlate with either changes in PVIRG or AIRG. Apparently, inferences regarding changes in PVDR of IRG cannot reliably be based solely on changes in hormonal concentrations, especially when measured only in the periphery. Moreover, since marked increases in peripheral plasma glucose levels were observed at times when PVDR of IRG was severely depressed following 20 and 30% hemorrhage it is suggested that glucagon may not play the dominant role in the early hyperglycemic response to hemorrhage.