title: T-type Ca2+ channels promote oxygenation-induced closure of the rat ductus arteriosus not only by vasoconstriction but also by neointima formation.
abstract: The ductus arteriosus (DA), an essential vascular shunt for fetal circulation, begins to close immediately after birth. Although Ca(2+) influx through several membrane Ca(2+) channels is known to regulate vasoconstriction of the DA, the role of the T-type voltage-dependent Ca(2+) channel (VDCC) in DA closure remains unclear. Here we found that the expression of alpha1G, a T-type isoform that is known to exhibit a tissue-restricted expression pattern in the rat neonatal DA, was significantly up-regulated in oxygenated rat DA tissues and smooth muscle cells (SMCs). Immunohistological analysis revealed that alpha1G was localized predominantly in the central core of neonatal DA at birth. DA SMC migration was significantly increased by alpha1G overexpression. Moreover, it was decreased by adding alpha1G-specific small interfering RNAs or using R(-)-efonidipine, a highly selective T-type VDCC blocker. Furthermore, an oxygenation-mediated increase in an intracellular Ca(2+) concentration of DA SMCs was significantly decreased by adding alpha1G-specific siRNAs or using R(-)-efonidipine. Although a prostaglandin E receptor EP4 agonist potently promoted intimal thickening of the DA explants, R(-)-efonidipine (10(-6) m) significantly inhibited EP4-promoted intimal thickening by 40% using DA tissues at preterm in organ culture. Moreover, R(-)-efonidipine (10(-6) m) significantly attenuated oxygenation-induced vasoconstriction by approximately 27% using a vascular ring of fetal DA at term. Finally, R(-)-efonidipine significantly delayed the closure of in vivo DA in neonatal rats. These results indicate that T-type VDCC, especially alpha1G, which is predominantly expressed in neonatal DA, plays a unique role in DA closure, implying that T-type VDCC is an alternative therapeutic target to regulate the patency of DA.
authors: Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan.
authors: Toru
authors: T
authors: Akaike
authors: Mei-Hua
authors: MH
authors: Jin
authors: Utako
authors: U
authors: Yokoyama
authors: Hiroko
authors: H
authors: Izumi-Nakaseko
authors: Qibin
authors: Q
authors: Jiao
authors: Shiho
authors: S
authors: Iwasaki
authors: Mari
authors: M
authors: Iwamoto
authors: Shigeru
authors: S
authors: Nishimaki
authors: Motohiko
authors: M
authors: Sato
authors: Shumpei
authors: S
authors: Yokota
authors: Yoshinori
authors: Y
authors: Kamiya
authors: Satomi
authors: S
authors: Adachi-Akahane
authors: Yoshihiro
authors: Y
authors: Ishikawa
authors: Susumu
authors: S
authors: Minamisawa
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020747:Calcium Channels, T-Type / Q000378:metabolism*; D004095:Dihydropyridines / Q000494:pharmacology; D004373:Ductus Arteriosus / Q000166:cytology / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009596:Nitrophenols / Q000494:pharmacology; D009924:Organ Culture Techniques; D009943:Organophosphorus Compounds / Q000494:pharmacology; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018078:Receptors, Prostaglandin E / Q000037:antagonists & inhibitors; D058309:Receptors, Prostaglandin E, EP4 Subtype; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D004095:Dihydropyridines; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D020033:Protein Isoforms; C545652:Ptger4 protein, rat; D018078:Receptors, Prostaglandin E; D058309:Receptors, Prostaglandin E, EP4 Subtype; C066425:efonidipine; D002118:Calcium