FRANKLIN, VATNER, HIGGINS, PATRICK, KEMPER AND VAN CITTERS 
1127 
lOOn 
RENAL BLOOD 
FLOW VELOCITY 50- 
cm/sec 
MEAN RENAL 
FLOW 
ml/min 
200-1 
ARTERIAL BLOOD 
PRESSURE lOOH 
mmHg 
RECLINE 
STAND 
GALLOP 
(I8mph-Av.s|^eed) 
I RECOVERY- 
STOP 
l I5min 30min 45min 
^^1^^ ^^^^^ 
MEAN 
PRESSURE 
mmHg 
HEART RATE 
beats/min 
MEAN RENAL 
RESISTANCE 
mmHg/ml/min 
0-" 
200-1 
100- 
0- 
300n 
100 
0 
.50-1 
.25- 
0- 
a 
4li 
^ 
t 
i±±£ 
5 
I sec 
Imin 
Figure 2. — A typical record of the renal response to severe exercise. From left to right the dog is reclining, then 
standing at rest, then running at an average speed of 18 mph, then resting during the recovery period. The 
phasic and mean values for renal blood flow and arterial pressure are shown along with computed heart rate 
and mean renal resistance. (Reprinted with permission from J. Clin. Invest. 50:1950, 1971). 
series of dogs.^^ Oxygen-carrying capacity was 
limited by induction of chronic severe anemia 
(progressive phlebotomy and volume replace- 
ment) in a third series of dogs. 2* In each of these 
situations of circulatory impairment severe ex- 
ercise produced much more intense visceral 
vasoconstriction than occurred in normal dogs 
resulting in sustained, marked reductions in 
visceral flows '^•23.24 (Figure 2). Thus, an impor- 
tant circulatory control mechanism was demon- 
strated only in the presence of circulatory im- 
pairment and could not be elicited in normal 
dogs. 
Although the peripheral vascular response to 
exercise was clarified in dogs, the question re- 
mained why the canine response is different 
from the responses observed during exercise in 
man."-^'^ Studies in man utilizing indirect tech- 
niques to measure blood flows, e.g., PAH, in- 
docyanine green, indicated that exercise reduces 
visceral blood flows and that the reduction in 
flow is roughly proportional to the severity of 
exercise. It is possible that the indirect tech- 
niques to measure regional flows in conscious 
man are not accurate indicators of total arterial 
inflow during exercise. For instance, it is possi- 
ble that renal arteriovenous shunting occurs 
during exercise, which would make the PAH 
clearance technique liable to serious error, since 
that technique would only measure flow to the 
peritubular glomerular vascular network. On 
the other hand, it is possible that a species dif- 
