Contractile responses of the human umbilical artery to KCl and serotonin in Ca-free medium and the effects of levcromakalim

Tufan H., Ayan-Polat B., Tecder-Ünal M., Polat G., Kayhan Z., Öǧüş E.

Life Sciences, vol.72, no.12, pp.1321-1329, 2003 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 72 Issue: 12
  • Publication Date: 2003
  • Doi Number: 10.1016/s0024-3205(02)02382-2
  • Journal Name: Life Sciences
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1321-1329
  • Keywords: umbilical artery, vascular smooth muscle, potassium channel, Ca-free, potassium, 5-hydroxytryptamine, ISOLATED RAT AORTA, SMOOTH-MUSCLE, INTERNAL MAMMARY, HUMAN PLACENTA, VASCULAR TONE, RABBIT AORTA, CALCIUM, CROMAKALIM, NIFEDIPINE, MODULATORS
  • Lokman Hekim University Affiliated: No


It is known that KATP channel openers inhibit the release and refilling of Ca2+ from intracellular stores. The present study was designed to test the effects of levcromakalim in human umbilical artery (HUA) rings stimulated by serotonin (5-HT) and KCl in Ca-free medium. Umbilical cords were obtained at vaginal or cesarean deliveries from healthy, term pregnancies. After the isolation, HUA rings were placed in organ baths in solution with indomethacin (10-5 M) and NG-nitro-L-arginine methyl ester (L-NAME) (10-3 M) at 37°C and aerated with 95% O2 and 5% CO2 for the measurement of isometric force. In Ca-free solution with Ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) (2 mM) the contractions produced by 5-HT (10-6 M) and KCl (40 mM) decreased significantly. Afterwards, HUA rings were treated with 5-HT and KCl in repeated manner in Ca-free medium. In contrast to KCl, 5-HT induced contractions reduced in each application, progressively. Levcromakalim (10-4 M) abolished the contractions elicited by 5-HT. On the other hand, levcromakalim had a little but significant inhibitory effect on KCl induced contraction in Ca-free medium. These results suggest that Ca2+ is not the only transduction pathway in KCl produced contractions of HUA smooth muscle cells. © 2002 Elsevier Science Inc. All rights reserved.