HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 70/4/1171    most recent biolreprod.103.024943v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Xiao, D. Articles by Zhang, L. Search for Related Content PubMed PubMed Citation Articles by Xiao, D. Articles by Zhang, L. Agricola Articles by Xiao, D. Articles by Zhang, L.

Calcium Homeostasis and Contraction of the Uterine Artery: Effect of Pregnancy and Chronic Hypoxia¹

Center for Perinatal Biology, Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, California 92350

The present study tested the hypothesis that chronic hypoxia alters pregnancy-mediated adaptation of Ca²⁺ homeostasis and contractility in the uterine artery. Uterine arteries were isolated from nonpregnant and near-term pregnant ewes of normoxic control or high-altitude (3820 m) hypoxic (oxygen pressure in the blood [PaO₂], 60 mm Hg) treatment for 110 days. Contractions and intracellular-free Ca²⁺ concentration ([Ca²⁺]_i) were measured simultaneously in the same tissue. In normoxic animals, pregnancy increased norepinephrine (NE), but not 5-hydroxy-thymide (5-HT) or KCl, contractile sensitivity in the uterine artery. Chronic hypoxia significantly attenuated NE-induced contractions in the pregnant, but not nonpregnant, uterine arteries. Similarly, 5-HT-mediated contractions of nonpregnant arteries were not changed. In the pregnant uterine artery, chronic hypoxia significantly increased NE-mediated Ca²⁺ mobilization, but decreased the Ca²⁺ sensitivity. In addition, hypoxia increased the calcium ionophore A23187-induced relaxation in pregnant, but not nonpregnant, uterine arteries. However, the A23187-mediated reduction of [Ca²⁺]_i was significantly impaired in hypoxic arteries. In contrast, hypoxia significantly increased the slope of the [Ca²⁺]_i-tension relationship of A23187-induced reductions in [Ca²⁺]_i and tension in the pregnant uterine artery. The results suggest that the contractility of nonpregnant uterine artery is insensitive to moderate chronic hypoxia, but the adaptation of sympathetic tone that normally occurs in the uterine artery during pregnancy is inhibited by chronic hypoxia. In addition, changes in Ca²⁺ sensitivity of myofilaments play a predominant role in the adaptation of uterine artery contractility to pregnancy and chronic hypoxia.

¹ Supported in part by NIH grants HL-57787, HL-67745, and HD-31226, and by Loma Linda University School of Medicine.

² Correspondence: Lubo Zhang, Center for Perinatal Biology, Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA 92350. FAX: 909 558 4029; lzhang{at}som.llu.edu

This article has been cited by other articles:

				H. Zhang and L. Zhang Role of Protein Kinase C Isozymes in the Regulation of alpha1-Adrenergic Receptor-Mediated Contractions in Ovine Uterine Arteries Biol Reprod, January 1, 2008; 78(1): 35 - 42. [Abstract] [Full Text] [PDF]

				H. Zhang and L. Zhang Regulation of {alpha}1-Adrenoceptor-Mediated Contractions of the Uterine Artery by Protein Kinase C: Role of the Thick- and Thin-Filament Regulatory Pathways J. Pharmacol. Exp. Ther., September 1, 2007; 322(3): 1253 - 1260. [Abstract] [Full Text] [PDF]

				D. Xiao, X. Huang, S. Yang, and L. Zhang Direct Effects of Nicotine on Contractility of the Uterine Artery in Pregnancy J. Pharmacol. Exp. Ther., July 1, 2007; 322(1): 180 - 185. [Abstract] [Full Text] [PDF]

				H. Zhang, D. Xiao, L. D. Longo, and L. Zhang Regulation of {alpha}1-adrenoceptor-mediated contractions of uterine arteries by PKC: effect of pregnancy Am J Physiol Heart Circ Physiol, November 1, 2006; 291(5): H2282 - H2289. [Abstract] [Full Text] [PDF]

				D. Xiao, J. N. Buchholz, and L. Zhang Pregnancy attenuates uterine artery pressure-dependent vascular tone: role of PKC/ERK pathway Am J Physiol Heart Circ Physiol, June 1, 2006; 290(6): H2337 - H2343. [Abstract] [Full Text] [PDF]

				S. M. Nauli, J. M. Williams, W. T. Gerthoffer, and W. J. Pearce Chronic hypoxia modulates relations among calcium, myosin light chain phosphorylation, and force differently in fetal and adult ovine basilar arteries J Appl Physiol, July 1, 2005; 99(1): 120 - 127. [Abstract] [Full Text] [PDF]

				D. Xiao and L. Zhang Adaptation of uterine artery thick- and thin-filament regulatory pathways to pregnancy Am J Physiol Heart Circ Physiol, January 1, 2005; 288(1): H142 - H148. [Abstract] [Full Text] [PDF]