1132 
MONITORING 
26. Vatner, S. F., Franklin, D., Higgins, C. B., Pat- 
rick, T., White, S., and Van Citters, R. L. Cor- 
onary dynamics in Unrestrained Conscious Ba- 
boons. Amer. J. Physiol. 221:1396, 1971. 
27. Vatner, S. F., Franklin, D., Higgins, C. B., Pat- 
rick, T., and Van Citters, R. L. Postprandial 
blood flow distribution in untethered baboons. (Ab- 
stract) Clin. Res. 20:402, 1972. 
28. Van Cittters, R. L., Franklin, D., Vatner, S. F., 
Patrick, T., and Warren, J. V. Cerebral hemo- 
dynamics in the giraffe. Trans, of the Assoc. of 
Amer. Phys. 82:293, 1969. 
DISCUSSION 
Chairman Franklin: So for those who 
didn't hear Dr. Scriabine's question, it was 
"How do you calibrate Konigsburg pressure 
gauges which are known to drift more-or-less 
over a period of time?" 
A. Scriabine, Merck Institute, Pennsylvania : 
Calibration is one problem, but the second part 
is the drifting and the recalibration. 
Dr. Vatner: That's true. We do calibrate 
these gauges before implantation and on the 
bench. But as you know, these implantable 
gauges do have some degree of drift and so 
what we do in any of these experiments, if it 
involves more than a day, is to do a Statham 
calibration simultaneously. For instance, at the 
end of a day of exercise studies, we'll catheterize 
the peripheral vessel and do a simultaneous 
Statham calibration. 
P. SOMANI, Abbott Laboratories, Chicago : 
You have very elegant studies showing normal 
and heart failure dogs. I wonder if your tests 
showed defect of digitalis glycoside in your 
model for heart failure and have seen it return 
to its normal values? 
Dr. Vatner: We have done digitalis studies 
in these heart failure dogs. We've mainly looked 
at the response of cardiac glycoside at rest. 
We've compared the peripheral vascular re- 
sponses to ouabain in normal dogs in which 
digitalis causes increases in resistance in the 
renal and iliac beds and a decrease in resistance 
in the renal and iliac beds and a decrease in 
resistance in the mesanteric bed. For these 
dogs, which have had heart failure induced, 
ouabain then causes increases in blood flow 
and decreases in resistance to all beds. So there 
is a difference in response to cardiac glycoside. 
We haven't looked at the response to glycoside | 
during exercise because we think that these 
dogs have mechanical lesions. This might be 
very difficult to overcome even with such a won- 
derful drug as digitalis. i 
C. G. La Farge, Children's Hospital, Boston : 
As always, the work of Dr. Franklin is perfectly | 
beautiful. I'm very envious because I picked the 
wrong animal, in that I don't have the advantage 
of the field trips that you must be able to take. 
I'm sorely troubled, though, by that business 
of the end-diastolic fiber length. I know it's been 
reported from race drivers in Indianapolis, of 
sinus tachycardia at rates of 250, that they 
maintain a perfectly satisfactory output for 
obvious reasons, but I'm bothered by the fact 
that a dog exercising maximally at a heart rate 
of 300 is still not only able to increase his end- 
diastolic fiber length and volume, but as your 
slide also implied, increasing the stroke volumes 
as well. Are you sure that that 0.2 fisec method 
that you're using for measurement may not re- 
flect geometric changes rather than an actual 
change in end-diastolic volume? 
Dr. Vatner: Well, I think just on a logical 
basis, if you want to, if you have some idea of 
the increases in cardiac output that must occur 
with this sort of exercise, the increases in heart 
rate that a dog normally gets from 80 to 300 
involves a 2i/^ fold increase in cardiac out- 
put. But when you measure cardiac output, you 
know that even with treadmill exercises, cardiac 
output rises more than 2.5 times control, and it 
probably rises about 4 or 5 times control. This 
severe exercise, which is much more severe than 
the treadmill exercise, almost has to cause an 
increase in stroke volume as well. For this rea- 
son as well as the fact that if there is a mis- 
alignment of the two crystals, we'll probably 
lose our signal altogether, because these are 
very sensitive to alignment. If the alignment 
changes, then we will get drop-outs, mistrigger- 
ings, and we won't get useful data. 
Dr. La Farge : Have you calculated the actual 
stroke volumes in the two situations, rest and 
severe exercise? 
Dr. Vatner : No, we haven't done that as yet. 
We're just going to. We just completed this 
study and we're going over the data right now. 
