AJP - Heart and Circulatory Physiology, Vol 241, Issue 6 883-H890, Copyright © 1981 by American Physiological Society
Hyperosmotic NaCl and severe hemorrhagic shock: role of the innervated lung
O. U. Lopes, V. Pontieri, M. Rocha e Silva Jr and I. T. Velasco
Infusions of hyperosmotic NaCl (2,400 mosmol/l; 4 ml/kg) were given to dogs
in severe hemorrhagic hypotension by intravenous injection (72 expts) or
intra-aortic injection (25 expts). In 46 experiments intravenous infusions
were given during bilateral blockage of the cervical vagal trunks (local
anesthesia or cooling). Intravenous infusions (without vagal blockade)
restore arterial pressure, cardiac output, and acid-base equilibrium to
normal and cause mesenteric flow to overshoot prehemorrhage levels by 50%.
These effects are stable, and indefinite survival was observed in every
case. Intra-aortic infusions of hyperosmotic NaCl produce only a transient
recovery of arterial pressure and cardiac output but no long-term survival.
Intravenous infusions with vagal blockage produce only a transient recovery
of cardiac output, with non long-term survival. Measurement of pulmonary
artery blood osmolarity during and after the infusions shows that a
different pattern is observed in each of these three groups and strongly
indicates that the first passage of hyperosmotic blood through the
pulmonary circulation at a time when vagal conduction is unimpaired is
essential for the production of the full hemodynamic-metabolic response,
which is needed for indefinite survival.
