Increased acetylcholine-induced vasodilation in pregnant rats: A role for gap junctional communication

Maria Fernanda Villela Dantas, Marcia Urban, David Spray, Maria Helena Catelli De Carvalho, Rita De Cassia Aleixo Tostes Passaglia

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

We have tested the hypothesis that increased gap junctional communication contributes to the augmented endothelium-dependent vasodilation in pregnancy. Contractile force and connexin43 expression were measured in aortic rings from nonpregnant and pregnant rats. Norepinephrine-constricted aortas from pregnant rats were more sensitive to acetylcholine, but not to sodium nitroprusside, compared with those from nonpregnant rats. Vessels from pregnant rats, constricted either with 45 mmol/L KCl or with norepinephrine± 10-4 mol/L N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide synthase, also exhibited greater relaxation to acetylcholine. Heptanol, an uncoupler of gap junctional communication, inhibited acetylcholine responses in norepinephrine-constricted aortas from nonpregnant rats but greatly impaired acetylcholine relaxation in aortas from pregnant rats. Heptanol also inhibited in both groups acetylcholine responses in vessels constricted with KCl, only minimally affected acetylcholine relaxation in arteries constricted with norepinephrine+L-NMMA, and did not change sodium nitroprusside-induced relaxation. Tetraethylammonium chloride induced greater contractions in control aortas compared with aortas from pregnant rats. Increased connexin43 mRNA levels were found in the uterus and in the roesenteric, uterine, and thoracic aortic arteries, but not in the heart and brain, from pregnant rats. These results suggest that increased gap junctional communication, possibly due to increased gap junction protein expression, may facilitate the effects of endothelium-derived relaxing factors, contributing to the augmented endothelium-dependent relaxation in arteries from pregnant rats.

Original languageEnglish (US)
Pages (from-to)937-942
Number of pages6
JournalHypertension
Volume34
Issue number4 II
DOIs
StatePublished - Oct 1999

Keywords

  • Endothelium-derived factor
  • Gap junctions
  • Nitric oxide
  • Preeclampsia
  • Rats

ASJC Scopus subject areas

  • Internal Medicine

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    Villela Dantas, M. F., Urban, M., Spray, D., Catelli De Carvalho, M. H., & Tostes Passaglia, R. D. C. A. (1999). Increased acetylcholine-induced vasodilation in pregnant rats: A role for gap junctional communication. Hypertension, 34(4 II), 937-942. https://doi.org/10.1161/01.hyp.34.4.937