Related Experiment Video
Updated: Jun 29, 2026

Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development
Published on: January 26, 2018
Large conductance Ca2+-activated K+ channels contribute to vascular function in nonpregnant human uterine arteries
Charles R Rosenfeld1, R Ann Word, Kevin DeSpain
1Division of Neonatal-Perinatal Medicine, Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, TX 75390, USA. charles.rosenfeld@utsouthwestern.edu
Abstract:
Large conductance K( +) channels (BK(Ca)) are expressed in uterine artery (UA) smooth muscle from nonpregnant and pregnant sheep and contribute to the regulation of basal vascular tone and responses to estrogen and vasoconstrictors. To determine if BK(Ca) are expressed in women and contribute to UA function, we collected UA from nonpregnant women (n = 31) at elective hysterectomy and analyzed for subunit protein, localization with immunohistochemistry, and function using endothelium-denuded rings. UA expresses BK(Ca) alpha -, beta1- and beta2-subunit protein. KCl and phenylephrine (PE, an alpha(1)-agonist) caused dose-dependent vasoconstriction (P < .001), and UA precontracted with PE dose-dependently relaxed with sodium nitroprusside (SNP; P < .001).Tetraethylammonium chloride (TEA, 0.2-1.0 mM), a BK(Ca) inhibitor, dose-dependently increased resting tone (P = .004; 28% +/- 5.3% with 1.0 mM), enhanced PE-induced (10(-)(6) M) vasoconstriction (P < .04), and attenuated SNP-induced relaxation at 1.0 mM (P = .02). BK( Ca) are expressed in human UA and modulate vascular function by attenuating vasoconstrictor responses and contributing to nitric oxide-induced vasorelaxation.
Related Concept Videos
Antihypertensive Drugs: Action of Calcium Channel Blockers
Autoregulation of Blood Flow
Chemical Signaling in Autoregulation
Chemical signaling operates at the precapillary sphincter level, inciting either contraction or relaxation.
Smooth Muscle Contraction
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
G-Protein Gated Ion Channels
Sensory organs,...
Nitric Oxide Signaling Pathway
Regulation of Angiogenesis and Blood Supply

