Haematological, blood gas and acid-base effects of central histamine-induced reversal of critical haemorrhagic hypotension in rats.
In a rat model of volume-controlled irreversible haemorrhagic shock, which results in a severe metabolic acidosis and the death of all control animals within 30 min., intracerebroventricular injection of histamine (100 nmol) produces a prompt and long-lasting increase in mean arterial pressure and heart rate, with a 100% survival of 2 h after treatment. Histamine action is accompanied by a decrease in haematocrit value, haemoglobin concentration, erythrocyte and platelet count, and an increase in residual blood volume at the end of the experiment (2 h). Cardiovascular effects are also associated with a long-lasting rise in respiratory rate and biphasic blood acid-base changes - initial increase of metabolic acidosis with the decrease in arterial and venous pH, bicarbonate concentration and base excess, followed by almost a complete recovery of blood gas and acid-base parameters to the pre-bleeding values, with normalisation of arterial and venous pH, Pco2 bicarbonate concentration and base excess at the end of experiment. It can be concluded that in the late phase of central histamine-induced reversal of haemorrhagic hypotension there is almost a complete restoration of blood gas and acid-base status due to circulatory and respiratory compensations, while accompanying haematological changes are the result of the haemodilution and the increase in residual blood volume.
Jochem
J
J
Department of Physiology, Silesian Medical University, Zabrze, Poland.
D000324:Adrenocorticotropic Hormone / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001784:Blood Gas Analysis; D006439:Hemodynamics / Q000187:drug effects; D006470:Hemorrhage / Q000097:blood / Q000188:drug therapy*; D006632:Histamine / Q000008:administration & dosage / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007022:Hypotension / Q000097:blood / Q000188:drug therapy*; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D006632:Histamine; D000324:Adrenocorticotropic Hormone