J. A. WILL, G. E. BISGARD, A. V. RUIZ AND R. F. GROVER 
269 
PERFUSION 
10 20 30 40 
PER CENT 
modify the regional distribution of Q and V/Q 
in the lung. 
In normal calves, pulmonary hypertension 
will develop whenever the hypoxic stimulus is 
of sufficient magnitude. Alveolar PO2 can be re- 
duced solely by lowering total atmospheric pres- 
sure at high altitude, e.g., at 3,400 m where Pb 
is 510 mmHg. However, alveolar PO2 will also 
decrease if alveolar ventilation is reduced. Bis- 
gard and Vogel,^ recently demonstrated that 
excision of carotid bodies in calves results in 
marked hypoventilation. The PaC02 increased 
by 20 mmHg while the PaOo decreased by 21 
mmHg. When the procedure was carried out at 
the moderate altitude of Denver, Colorado 
(1,600 m), the calves became sufficiently hy- 
poxic to develop pulmonary hypertension. How- 
ever, even though calves subjected to carotid 
-•SEA LEVEL •* ^2WEEKSH.A. ■■■ 
-■4WEEKS H A 
Figure 2. — Zonal distribution of perfusion (Q) and 
ventilation (V) at sea level (upper part) and after 
2 and 4 weeks at 3,400 m altitude (lower part) . Points 
are means ± standard error of the mean (S.E.). 
U 
P 
P 
E 
R 
M 
Z 
o 
N b 
E D 
S L 
J_ 
L 
O 
W 
E 
R 
VENTILATION 
20 30 
PER CENT 
40 
50 
in the distribution of Q. Thus, while these ob- 
servations indicate certain differences between 
the calf and man, nevertheless the calf is a very 
suitable model for the study of factors which 
u 
p 
p 
E 
R 
z "m 
O I 
N D 
1 
SEA LEVEL 
U 
P 
P 
E 
R 
z "m 
O I 
N D 
E 0 
L 
O 
W 
E 
R 
V-L 
]0 30 
PER CENT 
10 20 30 
PER CENT 
Figure 3. — Zonal distribution of V and Q during acute 
hypoxia and 100% O2 at sea level (upper part) and 
4 weeks at high altitude (lower part). Points are 
mean values ± S.E. 
Z M 
O ■ 
N D 
• ? 
S l_ 
I 
o 
w 
E 
R 
VENTILATION 
PERFUSION 
HIGH ALTITUDE 
U 
P 
P 
E 
R 
z "m 
O I 
N D 
E D 
S I 
E 
L 
O 
W 
E 
R 
20 30 40 
PER CENT 
-aKK>% ■•• 
■ 15% Oj 
20 30 
PER CENT 
-08% ©2 
