Adenosine modulates hypoxia-induced atrial natriuretic peptide release in fetal sheep.
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 micrograms.min-1.kg estimated fetal wt-1. Fetal arterial blood gases and pH were generally unaffected by adenosine, although mean arterial CO2 tension 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 approximately 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 control means (142-166 pg/ml) for the respective infusion rates of 8, 160, and 344 micrograms.min-1.kg estimated fetal wt-1. In seven fetuses, reducing fetal arterial O2 tension by approximately 9-10 Torr from a control of 23 +/- 1.3 Torr increased plasma ANP concentrations approximately 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 causes a dose-dependent rise in fetal plasma ANP concentrations and modulates fetal ANP release during hypoxia.
Ogunyemi
D A
DA
Department of Obstetrics and Gynecology, Nicholas S. Assali Perinatal Research Laboratory, UCLA School of Medicine 90024, USA.
Koos
B J
BJ
Arora
C P
CP
Castro
L C
LC
Mason
B A
BA
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001794:Blood Pressure; D005312:Fetal Blood / Q000378:metabolism*; D005740:Gases / Q000097:blood; D006339:Heart Rate; D006454:Hemoglobins / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D058915:Purinergic P1 Receptor Antagonists; D012756:Sheep; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
D005740:Gases; D006454:Hemoglobins; D058915:Purinergic P1 Receptor Antagonists; C031433:8-(4-sulfophenyl)theophylline; D009320:Atrial Natriuretic Factor; D013806:Theophylline; D000241:Adenosine