Osmolar changes in haemorrhage: the effects of an altered nutritional status.

Fed and 24-30 hour starved rats were submitted to haemorrhagic hypotension, 70 mmHg, with a modified Wigger's system. Neuroleptanalgesia was used to ensure a normal degree of stress reactivity. Despite fed animals losing 53% of their original blood volume (BV) and starved animals 47% (BV = 6% prestarved body weight), blood gas data and creatinine levels confirmed a well intact and compensated status in both groups. Fed animals compensated for the greater haemorrhage with a haematocrit reduction which was double that in starved animals. When the alterations in osmole skeletons were compared, evidence for an intracellular fluid (ICF) shift to the interstitium was obtained in fed rats. Their NaCl space increased by 5.5%. Glucose increased its osmolar effect by 224% among fed animals and was reduced in those which had been starved. Glucose was identified as the solute causing an acute mobilisation of ICF to the interstitium.