WILLIAM F. FRIEDMAN 
747 
18. Anden, N. E., Magneusen, T., and Waldeck, B. 
Correlation between noradrenaline uptake and ad- 
renergic nerve function after reserpine treatment. 
Life Sci. 3:19, 1964. 
19. Crout, J. R., MusKus, A. J., and Trendelen- 
burg, U. Effect of tyramine on isolated guinea pig 
atria in relation to their noradrenaline stores. Brit. 
J. Pharmacol. 18:600, 1962. 
20. CovELL, J. W., Chidsey, C. a., and Braunwald, 
E. Reduction of the cardiac response to post-gan- 
glionic sympathetic nerve stimulation in experimen- 
tal heart failure. Circulation Res. 19:51, 1966. 
DISCUSSION 
Francis Cavoto, Medical College of Pennsyl- 
vania, Phila. : You alluded to the fact that the 
rat also shows the same delay after birth in de- 
veloping a sympathetic nervous system. What 
time schedule is that? 
Dr. Friedman : It was very similar to the 
rabbit curve. By about three to four weeks of 
age, the uptake of cardiac tritiated catechola- 
mines, for example, are equivalent to the adult 
in the rat. 
Chairman Cohen: Bill, do you have any 
idea what the stimulus is to change the fetal re- 
sponse to the adult after birth. 
Dr. Friedman : Thus far the answer to that 
would just be conjecture. We are now studying 
the chronically instrumented fetus where we 
can adjust conditions in utero and then see 
if, at term, we have altered such things as 
cardiac catecholamines. Currently, we are study- 
ing alterations in baroreceptor stimuli during 
fetal life with chronically implanted sono- 
micrometers on the endocardial surface of 
the left ventricle. The results are not yet in 
with regard to whether there will be a differ- 
ence in the extent and distribution of sympa- 
thetic nerves at the time of birth because of all 
this sensory input during fetal life, 
PiTAMBAR Somani, Abbott Laboratories, 
North Chicago : You alluded to the fact that nor- 
epinephrine concentration in fetal heart is 
very low, and also that the enzymes for syn- 
thesis are quite low. Can you tell us whether in- 
nervation is complete at this point and is it only 
a question of lack of enzymes, or is the nerve 
development also incomplete at this point? 
Dr. Friedman : I can't be terribly specific. It 
would appear that all of this is a reflection of 
incomplete innervation, rather than a question 
of enzyme induction. That would be my guess. 
It is not corroborated by hard scientific data at 
this point. 
