Effects of haemorrhagic hypotension on brain and liver metabolism in normotensive (WKY) and spontaneously hypertensive rats (SHR).

Hypertensive disease is known to increase the risks in connection with acute changes in blood pressure due to the presence of pronounced structural as well as functional changes in the cardiovascular system. In the present study the metabolic consequences of fixed haemorrhagic hypotension [mean arterial pressure (MAP) 70 and 45 mmHg] were studied in spontaneously hypertensive (SHR) and in normotensive rats (WKY). Blood gases and acid-base balance, blood glucose, liver (ATP, glucose, lactate) and brain (ATP, ADP, AMP, CP, glucose, lactate) metabolites were determined in unbled animals and after 35 min hypotension in bled animals. In the liver haemorrhage to MAP 70 mmHg resulted in a 70% reduction of the ATP content in SHR while that in WKY remained unchanged. At MAP 45 mmHg reduced liver ATP levels (35% reduction) were observed in WKY as well. In the brain metabolic changes indicative of tissue ischaemia (reduced CP, increased AMP and lactate, decreased energy charge potential) were present only in SHR at MAP 45 mmHg. The more pronounced metabolic disturbances in SHR than in WKY indicate that blood loss is more deleterious for the hypertensive individual.