Prostacyclin synthesis and stimulation of cyclic AMP production in ovine fetal vasculature: Heterogeneity in pulmonary and systemic arteries

P. W. Shaul, M. A. Farrar, R. R. Magness

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Prostacyclin (PGI2) is an important local mediator of vasomotor tone in the fetus and newborn, acting via stimulation of cAMP production by vascular smooth muscle (VSM) adenylate cyclase. In this investigation PGI2 and prostaglandin (PG) E2 synthesis and stimulation of cAMP production were compared in vitro in ovine fetal pulmonary versus systemic (mesenteric) arteries. PGI2 synthesis was similar in the pulmonary and systemic arteries (2.4 ± 0.2 and 2.6 ± 0.3 ng/mg protein-h, respectively), as was PGE2 synthesis (1.9 ± 0.2 and 1.5 ± 0.2 ng/mg protein h, respectively); synthesis was greater for PGI2 versus PGE2 in both artery types. 65-71% of PGI2 synthesis and 51-59% of PGE2 synthesis occurred in the endothelium. Basal (nonstimulated) cAMP production was fully attenuated by indomethacin, indicating that it is mediated exclusively by endogenous PG. Basal cAMP production was 3.8-fold less in pulmonary versus systemic arteries, and this was related to a 9.7-fold difference in responsiveness to PG. A 14.7-fold difference in the response to forskolin indicates that underlying mechanism may be a disparity in the quantity and/or function of the adenylate cyclase enzyme complex. Thus, prostacyclin and PGE2 synthesis are comparable in ovine fetal pulmonary versus systemic arteries, but the cAMP response to the prostanoids is markedly greater in the latter artery type due to differences in the activation of adenylate cyclase. This heterogeneity in VSM intracellular signalling may contribute to differential vasomotor tone and responses in the fetal pulmonary and systemic circulation.

Original languageEnglish (US)
Pages (from-to)89-99
Number of pages11
JournalDevelopmental Pharmacology and Therapeutics
Volume18
Issue number1-2
StatePublished - Dec 1 1992

Keywords

  • Cyclic AMP
  • Fetus
  • Mesenteric artery
  • Prostacyclin
  • Prostaglandin E
  • Pulmonary artery

ASJC Scopus subject areas

  • Pharmacology, Toxicology and Pharmaceutics(all)
  • Pharmacology (medical)

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