Cardiovascular effects of a mu-selective opioid agonist (tyrosine-D-arginine-phenylalanine-lysine-NH2) in fetal sheep: Sites and mechanisms of action

Citation
Ys. Holsey et al., Cardiovascular effects of a mu-selective opioid agonist (tyrosine-D-arginine-phenylalanine-lysine-NH2) in fetal sheep: Sites and mechanisms of action, AM J OBST G, 180(5), 1999, pp. 1127-1130
Citations number
16
Categorie Soggetti
Reproductive Medicine","da verificare
Journal title
AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY
ISSN journal
00029378 → ACNP
Volume
180
Issue
5
Year of publication
1999
Pages
1127 - 1130
Database
ISI
SICI code
0002-9378(199905)180:5<1127:CEOAMO>2.0.ZU;2-5
Abstract
OBJECTIVE: We investigated the effects of DALDA (tyrosine-D-arginine-phenyl alanine-lysine-NH2), a mu-selective opioid peptide, on heart rate and blood pressure in fetal sheep with long-term instrument implantation. STUDY DESIGN: DALDA was given as an intravenous bolus in doses ranging from 0.15 to 0.5 mg/kg. A 0.5 mg/kg dose of DALDA was given in the presence of the opioid antagonist naloxone and its quaternary analog naloxone methiodid e (6 mg/h); it was also given in conjunction with the beta-adrenergic antag onist propranolol (2 mg/h). Statistical analyses were performed by 1-way an d 2-way analysis of variance. RESULTS: The fetus responded to DALDA with an increase in heart rate with a ll doses (P <.01) but without any change in blood pressure. This response w as abolished by naloxone (P <.001), naloxone methiodide (P =.003), and prop ranolol (P <.001). CONCLUSIONS: In the fetus intravenous DALDA increases heart rate without an y change in blood pressure by way of the mu receptor and through central sy mpathetic activation. These effects of DALDA are different from those seen in the adult, suggesting different sites and mechanisms of action.