This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ruttner, Z. Articles by Ligeti, L. Search for Related Content PubMed PubMed Citation Articles by Ruttner, Z. Articles by Ivanics, T. Articles by Slaaf, D. W. Articles by Reneman, R. S. Articles by Toth, A. Articles by Ligeti, L. Social Bookmarking                   What's this?

In Vivo Monitoring of Intracellular Free Calcium Changes During Uterine Activation By Prostaglandin F2 and Oxytocin

Semmelweis University, Faculty of Medicine, Institute of Human Physiology and Clinical Experimental Research, Budapest, Hungary; Departments of Biophysics and Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands ruttner{at}elet2.sote.hu

Tamas Ivanics, MD, PhD

Dick W. Slaaf, PhD

Robert S. Reneman, MD, PhD

Andras Toth, PhD

Laszló Ligeti, MD, PhD

Semmelweis University, Faculty of Medicine, Institute of Human Physiology and Clinical Experimental Research, Budapest, Hungary; Departments of Biophysics and Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands

Objective: It has been well established that oxytocin (OXT) increases intracellular free calcium ([Ca²⁺]_i) by targeting both intracellular and extracellular stores, but the mechanisms involved in the increase through activation with prostaglandin F₂ (PGF₂) are still incompletely understood. This study was designed to elucidate the source(s) of increased [Ca²⁺]_i in response to PGF₂ (10^-6 M) or OXT (10^-8 M) administration in the near-term rat myometrium.

Methods: The animals were divided into an in vitro group (n = 8), where the developed tension of uterine strips was assessed, and an in vivo group (n = 5), where a lobe of the uterus with intact innervation and circulation was loaded with the fluorescent indicator Indo-1 AM to assess [CA²⁺]_i.

Results: PGF₂ and OXT induced a 30.1% and 35.9%, respectively, increase in developed tension in the potassium chloride-depolarized myometrial strips. Nifedipine reduced the PGF₂ and OXT increased tension by 65.8% and 49.4%, respectively. In vivo, both PGF₂ and OXT increased [Ca²⁺]_i in the pottassium chloride-depolarized uterine muscle by 35.7% and 44.6%, respectively, increases similar to the rises in tension in vitro. Nifedipine reduced these effects of PGF₂ and OXT by 45.3% and 39.6%.

Conclusions: These findings indicate that in near-term myometrium the source of increased [Ca²⁺]_i after administration of PGF₂, similar to OXT, is both extracellular and intracellular.

Key Words: Endocrine regulation • microcirculation • myometrial contraction

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?