Vol. 86, Issue 5, 1617-1625, May 1999
Acid-base disturbance during hemorrhage in rats: significant
role of strong inorganic ions
V.
Alfaro,
J.
Pesquero, and
L.
Palacios
Departamento de Fisiología, Facultad de
Biología, Universidad de Barcelona, E-08028 Barcelona,
Spain
The
present study tests the hypothesis that changes in the strong inorganic
ion concentrations contribute significantly to the acid-base
disturbance that develops during hemorrhage in the arterial plasma of
rats in addition to lactate concentration
([Lac
])
increase. The physicochemical origins for this acid-base disorder were
studied during acute, graded hemorrhage (10, 20, and 30% loss of blood
volume) in three groups of rats: conscious, anesthetized with ketamine,
and anesthetized with urethan. The results support the hypothesis
examined: strong-ion difference (SID) decreased in the arterial plasma
of all groups studied because of an early imbalance in the main strong
inorganic ions during initial hemorrhagic phase. Moreover, changes in
plasma [Lac]
contributed to SID decrease in a later hemorrhagic phase (after 10%
hemorrhage in urethan-anesthetized, after 20% hemorrhage in ketamine-anesthetized, and after 30% hemorrhage in conscious group). Inorganic ion changes were due to both dilution of the vascular compartment and ion exchange with extravascular space and red blood
cells, as compensation for blood volume depletion and hypocapnia. Nevertheless, anesthetized rats were less able than conscious rats to
preserve normal arterial pH during hemorrhage, mainly because of an
impaired peripheral tissue condition and incomplete ventilatory compensation.
strong-ion difference; ion imbalance; metabolic acidosis; anesthesia; ketamine; urethan
