Hydrogen Sulfide Relaxes Human Uterine Artery by Activating Smooth Muscle BKCa Channels: A Recent Study | Chapter 13 | New Horizons in Medicine and Medical Research Vol. 10

 Background: Vasodilation is mediated by hyperpolarizing smooth muscle (SM) plasma membranes when large conductance calcium-activated and voltage-dependent potassium (BKCa) channels open, which is a critical mechanism for mediating uterine artery (UA) dilatation during pregnancy. Despite the fact that H2S has recently been discovered as a novel UA vasodilator, the mechanisms behind H2S-induced UA dilation remain unexplained.

The goal of this study is to find out how H2S relaxes human UA.

Methods: During a caesarean hysterectomy, pregnant women's main uterine arteries were taken. For electrophysiological experiments, primary smooth muscle cells were extracted and grown. Immunofluorescence microscopy, Western blot, and RT-PCR were used to determine the protein and mRNA expression of BKCa channels. For organ bath experiments, freshly produced uterine artery rings were employed.

Multiple BKCa subunits have been identified in human UA and hUASMC cells in vitro, with high 1and 1proteins localised in SM cells. Iberiotoxin (IBTX) and tetraethylammonium, two BKCa blockers, drastically reduced baseline outward currents. In a dose-dependent manner, H2S enhanced BKCa currents and channel open probability. The Ca2+ blocker nifedipine (5 M) and the chelator ethylene glycol-bis(-aminoethyl ether)-tetraacetic acid (EGTA, 5 mM) had no effect on H2S-potentiated BKCa currents or open probability. NaHS relaxed phenylephrine-pre-constricted newly formed human UA rings in a dose-dependent manner, which was blocked by IBTX.

Conclusions: H2S induces UA relaxation in humans, at least in part, via activating SM BKCa channels that are not reliant on external Ca2+.

Author(S) Details

Yan Li
Department of Obstetrics and Gynecology, University of California, Irvine, CA 92697, USA.

Jin Bai
Department of Obstetrics and Gynecology, University of California, Irvine, CA 92697, USA.

Yi-hua Yang
Department of Obstetrics and Gynecology, University of California, Irvine, CA 92697, USA.

Naoto Hoshi
Department of Pharmacology, University of California, Irvine, CA 92697, USA.

Dong-bao Chen
Department of Obstetrics and Gynecology, University of California, Irvine, CA 92697, USA.

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