AJP - Heart and Circulatory Physiology, Vol 256, Issue 1 240-H246, Copyright © 1989 by American Physiological Society
Vascular development in chick embryos: a possible role for adenosine
T. H. Adair, J. P. Montani, D. M. Strick and A. C. Guyton
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216-4505.
We studied the possible role of adenosine in the development of the
vasculature using 217 chick embryos. Adenosine (2-32 mumol/day), inosine
(16 mumol/day), dipyridamole (0.04-0.4 mumol/day), or aminophylline (400
and 800 micrograms/day) were administered twice each day into the air space
on days 11-14. Control embryos received Ringer solution. Whole body
vascularity was estimated on day 15 as the whole body structural vascular
resistance (SVR), i.e., the hydraulic resistance of the maximally dilated
vasculature. Adenosine decreased the SVR in a dose-related manner at the
lower dosage amounts but caused a maximum decrease in SVR at the higher
dosage amounts averaging 30% below the Ringer control values. Equimolar
amounts of adenosine and inosine decreased the SVR by the same extent.
Dipyridamole, which potentiates the biological effects of endogenous
adenosine, also decreased the SVR in a dose-related manner to values
averaging approximately 30% below control. When the effects of endogenous
adenosine were blocked by aminophylline, the SVR increased in a
dose-related manner to approximately 100% above control at the highest
dosage amount. These results suggest that adenosine could have a
physiological role in growth regulation of the vascular system in the chick
embryo.
