Adenosine modulates hypoxia-induced atrial natriuretic peptide
release in fetal sheep.
Ogunyemi, Dotun A., Brian J. Koos, Chander P. Arora, Lony C. Castro,
and Brian A. Mason.
Department of Obstetrics and Gynecology, Nicholas S. Assali
Perinatal Research Laboratory, UCLA School of Medicine, Los Angeles,
CA 90024; and the Department of Obstetrics and Gynecology, Cedars
Sinai Research Institute, Cedars Sinai Medical Center, Los Angeles,
CA 90048
APStracts 2:0174H, 1995.
The effects of adenosine on atrial natriuretic peptide (ANP) secretion
were determined in chronically catheterized fetal sheep (>0.8
term). Adenosine was infused into the the right jugular vein for 1 h
at 8 +/- 0.4 (5 fetuses), 160 +/- 8 (6 fetuses), and 344 +/- 18
_g/min per kg fetal weight. Fetal arterial blood gases and pH were
generally unaffected by adenosine, although mean PaCO2 increased
transiently by 2-5 Torr and pH fell progressively during the highest
rate of infusion. During the intermediate and high infusion rates,
fetal hemoglobin concentrations increased by 11-13% and mean fetal
heart rate rose by 18% from a control value of about 167 beats/min.
Mean arterial pressure was not affected during adenosine infusion.
Adenosine significantly increased fetal plasma ANP levels with
maximum concentrations 1.80, 2.36, and 2.51 times greater than the
control means (142-166 pg/ml) for the respective infusion rates of 8,
160, and 344 _g/min/kg fetal weight. In 7 fetuses, reducing fetal
PaO2 by about 9-10 Torr from a control of 23 +/- 1.3 Torr increased
plasma ANP concentrations about 2.4 times the control mean of 176
pg/min. Adenosine receptor blockade with 8-(p-sulfophenyl)
-theophylline reduced by 50% the maximum hypoxia-induced rise in
plasma ANP concentrations. It is concluded that adenosine 1) causes a
dose-dependent rise in fetal plasma ANP concentrations, and 2)
modulates fetal ANP release during hypoxia.
Received 20 July 1994; accepted in final form 27 January 1995.
APS Manuscript Number H639-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 2 May 1995.