Cyclic AMP and metabolic substrates in hemorrhagic shock of the rat.

Hemorrhagic shock was induced in rats by bleeding to 35 mmHg for a period of 4 h. Plasma glucose increased rapidly following the onset of bleeding and reached twice the control value after 30 min. After 2 h hypotension the liver content of glycogen was depleted and subsequently the rats became hypoglycemic. The rise in plasma glucose was accompanied by a rise in plasma cyclic AMP, which was 10-fold after 1 h, but returned towards control values at the end of the hypotensive period. There were no corresponding changes in the cyclic AMP contents of liver, heart or adipose tissue. Blood lactate was increased 10-fold and the lactate/pyruvate ratio was more than doubled, suggesting an increased anaerobic metabolism. Plasma FFA levels fell significantly, while plasma glycerol was unchanged during the hypotensive period. In this hemorrhagic shock model there is an initial phase of glucose mobilization from the liver, which is accompanied by elevated plasma cyclic AMP. This phase is followed by a period of depressed levels of glucose as well as FFA and thus a lack of metabolizable substrates in plasma.