The role of blood glucose in defense of plasma volume during hemorrhage.

The purpose of this study was to assess the importance of the hyperglycemic response in defense of plasma volume during hemorrhagic shock. Normal well-fed white rats were divided into four groups of 10 each. Two shock models were used each containing rats fasted for 24 hr and control rats maintained on a standard diet. All rats had free access to water. Hemorrhage was produced either by bleeding to a constant mean arterial blood pressure of 40 mm Hg or by removing a fixed per cent of blood volume at 30-min intervals. All control animals withstood a larger volume of blood loss and survived longer than fasted animals, regardless of which shock model was used. They also manifested a significantly greater mean maximum per cent rise in blood glucose and decline in hematocrit during hypovolemia. A change in blood glucose was correlated with change in hematocrit, and to the extent that the latter is a reflection of plasma refill, fed animals demonstrated a greater ability to refill lost plasma volume. The strong correlation between glucose levels and hematocrit during all phases of hypovolemic shock indicates that blood glucose may be an important determinant of plasma refill. The mechanisms whereby glucose exerts these effects may involve its role as an osmotic agent and as a substrate for energy metabolism.