68 
CARDIAC MODELS 
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5a 5b 
Figure 5. — Aortic nerve (left panels) and renal post- 
ganglionic sympathetic nerve (right panels) activity 
in experimental cardiogenic shock. In each panel 
from top to bottom the recordings represent the fol- 
lowing: integrated and mean nerve activity; actual 
nerve recording; EGG; aortic pressure (with mean 
pressure). Panels 1 and 2: control recordings; panels 
3 and 4: recording during cardiogenic shock state; 
panels 5a and 6a: recording before cutting vagi 
(shock state) ; panels 5b and 6b after cutting vagi. 
Note decrease of aortic (3 and 5a) and sympathetic 
(4 and 6a) activity in shock and increase after cut- 
ting vagi (5b and 6b). 
drawal and inhibit the expected compensatory- 
increase of sympathetic discharge. From other 
experiments in non-shock animals, we have rea- 
son to beheve that these reflexes originate in the 
left ventricle and are activated by increased 
stretching of the ventricular v^^all due to the 
acutely increased end-diastolic volume present 
in cardiogenic shock. The Bezold-Jarish reflex 
may also participate initially. We are trying at 
the present to separate the function of these 
two types of reflexes in cardiogenic shock. 
Mean Aortic N. Activity 
■•'MlTOIIIV ONLY) 
Mean Sympathetic N. Activity 
(VAGOTOMY ONLY) 
+30 
0 
O)-20 
c 
J -40) 
+20 H, 
0 
« 
g)_20 
D 
X-40 
.0-60 
\ 
Time (lirs.) 
Mean Aortic N. Activity 
3 4 
.01) iPB-2B) 
+20 
0 
C 
u 
lATROPINC + VACOTOMY) 
Time (jirs-f 
Mean SympatlieticN. Activity 
Atropln* V«i*tomv 
+20- 
0- 
20 
-40 
.0-60 
S. 
Time 
A. 
IP- .ou 
V. 
(Pi.01) 
Hi 
J 
'ATROPINE 4- VAGOTOMY) 
At rap I M VaiotMny 
s. 
Time 
A. V. 
(Pa.OO) 1P>.2S 
Figure 6. — Average aortic nerve and sympathetic 
nerve activity before and during shock and after va- 
gotomy (upper panels) in eight dogs and the re- 
sponse to atropine and vagotomy during shock in five 
dogs (lower panels). Vertical lines are standard er- 
rors of the mean. 
The reported findings of increased catecho- 
lamines during myocardial infarction may not 
be contrary to the decreased sympathetic activ- 
ity since they originate mainly in the adre- 
nal medulla and not in the sympathetic nerve 
VAGOTOMY - GROUP 
Mean Sys. Blood Pressure Mean Heart Rate 
-50 
B. 1 
Time (hrs.) 
Mean Cardiac Output 
-50 
B. I 2 3 
Time (iirs.) 
Mean Peripheral Resistance 
E 
CO 
w 
-50 
+50 
B. I 
Time (hrs.) 
2,3 4 
(p=.oil 
. lP=.Ol) 
Time (hrs.) 
Figure 7. — Hemodynamic changes in eight dogs before 
and after cardiogenic shock and after vagotomy. 
