AJP - Regulatory, Integrative and Comparative Physiology, Vol 237, Issue 3 203-R209, Copyright © 1979 by American Physiological Society
Sinovagal interaction in arterial pressure restoration after 10% hemorrhage
H. Hosomi and K. Sagawa
The summation between the carotid sinus baroreceptor reflex system (CS
system) and the vagally mediated reflex system (V system) was studied as
they restore mean arterial pressure (MAP) after 10% quick hemorrhage in
splenectomized conscious dogs chronically instrumented with catheters for
pressure measurement and hemorrhage. The experiment was repeated under
nerve-intact condition (intact), with cold block of the vagi ([V]), after
carotid sinus denervation (CS), and CS plus [V] situations. MAP falls at
1.5 min after the hemorrhage were 7.2 in intact, 24.7 in [V], 36.0 in CS,
and 67.6 in CS + [V] mmHg. When we calculated the open-loop gains of CS and
V systems assuming a simply additive summation between them a
self-contradiction occurred. To avoid this contradiction, it was necessary
to assume that CS and V systems interact in a facilitatory manner. Mean
open-loop gains calculated under this assumption were 1.64 for the CS
system alone, 0.89 for the V system alone, and 6.59 for the interacting
component between them. These intriguing results warrant further analysis
of the summation between the two reflex systems.
