1. Functional effects of urotensin-II on intracellular pH regulators in human radial artery smooth muscle cells.
- Author
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Loh SH, Chang CY, Huang SF, Chao SC, Lin WK, Huang EY, Tsai CS, and Tsai YT
- Subjects
- Cytoplasm metabolism, Dose-Response Relationship, Drug, Humans, Hydrogen-Ion Concentration, Myocytes, Smooth Muscle cytology, Myocytes, Smooth Muscle metabolism, Myocytes, Smooth Muscle physiology, Radial Artery cytology, Radial Artery metabolism, Radial Artery physiology, Sodium-Hydrogen Exchangers metabolism, Myocytes, Smooth Muscle drug effects, Radial Artery drug effects, Urotensins pharmacology
- Abstract
The regulation of intracellular pH (pH
i ) plays a vital role in various cellular functions. We previously demonstrated that three different acid extruders, the Na+ -H+ exchanger (NHE), Na+ -HCO3 - co-transporter (NBC) and H+ -linked monocarboxylate transporter (MCT), functioned together in cultured human radial artery smooth muscle cells (HRASMCs). However, the functions of acid-loading transporters in HRASMCs remain poorly understood. Urotensin II (U-II), one of the most potent vasoconstrictors, is highly expressed in many cardiovascular diseases. The aim of this present study was to determine the concentration effect of U-II (3 pM∼100 nM) on the functional activity of pHi regulators in HRASMCs. Cultured HRASMCs were derived from segments of human radial arteries obtained from patients undergoing bypass grafting. Changes in pHi recovery due to intracellular acidification and alkalization induced by NH4 Cl prepulse and Na-acetate prepulse, respectively, were detected by microspectrofluorimetry with the pH-sensitive fluorescent dye BCECF. Our present study showed that (a) U-II increased the activity of NHE in a concentration-dependent manner but did not change that of NBC or MCT or resting pHi , (b) the Cl- -OH- exchanger (CHE) facilitated base extrusion, and (c) U-II induced a concentration-dependent increase in the activity of CHE. In conclusion, for the first time, our results highlight a concentration-dependent increase in the activity of NHE and CHE, but not NBC and MCT, induced by U-II in HRASMCs., Competing Interests: Declaration of Competing Interest The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2019. Published by Elsevier Inc.)- Published
- 2020
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