The effect of centrally administered adenosine on fetal breathing movements.
The central effects of the adenosine analogue L-2-N6-(phenylisopropyl) adenosine (L-PIA) on breathing movements was determined by making injections into the fourth ventricle in unanesthetized fetal sheep. Administration of 0.5 micrograms L-PIA reduced the percent time during which fetal breathing occurred from 48.0 +/- 5.2 (SEM) to 19.5 +/- 6.1. Inspiratory slope was reduced to 62 +/- 5.5 and to 43 +/- 5.7 percent of the control values when 0.2 and 0.5 micrograms L-PIA were given respectively. The effects of L-PIA on the percent time fetal breathing movements occurred and on inspiratory slope were prevented by the prior systemic administration of theophylline (plasma concentrations approximately 15 micrograms/ml). When the vehicle for L-PIA, dimethyl sulfoxide in Ringer solution was given into the fourth ventricle or when 0.5 micrograms L-PIA was given systemically, there was no effect on fetal breathing. None of these protocols resulted in a change in sagittal sinus blood pH, PO2 or, PCO2. These data indicate adenosine acts at the brain stem to depress fetal respiratory drive.
Bissonnette
J M
JM
Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland 97201-3098.
Hohimer
A R
AR
Knopp
S J
SJ
D000241:Adenosine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005333:Fetus / Q000187:drug effects* / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007276:Injections, Intraventricular; D011247:Pregnancy; D011659:Pulmonary Gas Exchange; D012119:Respiration / Q000187:drug effects* / Q000502:physiology; D012756:Sheep; D013806:Theophylline / Q000097:blood / Q000494:pharmacology
D013806:Theophylline; D000241:Adenosine