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Characterization of the molecular and electrophysiological properties of the T-type calcium channel in human myometrium

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Blanks, Andrew M., Zhao, ZhengHang Zhao, Shmygol, Anatoly , Bru-Mercier, Gilles , Astle, Shirley and Thornton, Steve. (2008) Characterization of the molecular and electrophysiological properties of the T-type calcium channel in human myometrium. The Journal of Physiology, Vol.581 (No.3). pp. 915-926. ISSN 0022-3751

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Official URL: http://dx.doi.org/10.1113/jphysiol.2007.132126

Abstract

Rises in intracellular calcium are essential for contraction of human myometrial smooth muscle (HMSM) and hence parturition. The T-type calcium channel may play a role in this process. The aim was to investigate the role of the T-Type calcium channel in HMSM by characterizing mRNA expression, protein localization, electrophysiological properties and function of the channel subunits Cav3.1(α1G), Cav3.2(α1H), and Cav3.3(α1I). QRT-PCR, immuno-histochemistry, electrophysiology and invitro contractility were performed on human myometrial samples from term, preterm, labour and not in labour. QRT-PCR analysis of Cav3.1, Cav3.2 and Cav3.3 demonstrated expression of Cav3.1 and Cav3.2 with no significant change (P>0.05) associated with gestation or labour status. Immuno-histochemistry localized Cav3.1 to myometrial and vascular smooth muscle cells whilst Cav3.2 localized to vascular endothelial cells and invading leukocytes. Voltage clamp studies demonstrated a T-type current in 55% of cells. Nickel block of T-type current was voltage sensitive (IC50 of 118.57±68.9 μM at - 30mV). Activation and inactivation curves of ICa currents in cells expressing T-type channels overlapped demonstrating steady state window currents at the resting membrane potential of myometrium at term. Current clamp analysis demonstrated that hyperpolarizing pulses to a membrane potential greater than -80mV elicited rebound calcium spikes that were blocked reversibly by 100μM nickel. Contractility studies demonstrated a reversible decrease in contraction frequency during application of 100μM nickel (P<0.05). We conclude that the primary T-type subunit expressed in some MSMCs is Cav3.1. We found that application of 100 μM nickel to spontaneously contracting human myometrium reversibly slows contraction frequency.

Item Type:	Journal Article
Subjects:	R Medicine > R Medicine (General)
Divisions:	Faculty of Medicine > Warwick Medical School
Library of Congress Subject Headings (LCSH):	Myometrium, Parturition, Calcium channels
Journal or Publication Title:	The Journal of Physiology
Publisher:	Blackwell
ISSN:	0022-3751
Date:	14 July 2008
Volume:	Vol.581
Number:	No.3
Page Range:	pp. 915-926
Identification Number:	10.1113/jphysiol.2007.132126
Status:	Peer Reviewed
Access rights to Published version:	Open Access
Description:	Final version (published as open access).
Related URLs:	Publisher
References:	2 Anwer K, Oberti C, Perez GJ, Perez-Reyes N, McDougall JK, Monga M, Sanborn BM, 3 Stefani E & Toro L. (1993). Calcium-activated K+ channels as modulators of human myometrial contractile activity. Am J Physiol 265, C976-985. 45 6 Astle S, Thornton S & Slater DM. (2005). Identification and localization of prostaglandin 7 E2 receptors in upper and lower segment human myometrium during pregnancy. Mol Hum Reprod 11, 279-287. 89 10 Challis JRG, Matthews SG, Gibb W& Lye SJ. (2000). Endocrine and paracrine 11 regulation of birth at term and preterm. Endocr Rev 21, 514-550. 12 13 Cribbs LL, Lee JH, Yang J, Satin J, Zhang Y, Daud A, Barclay J, Williamson MP, Fox 14 M, Rees M & Perez-Reyes E. (1998). Cloning and characterization of alpha1H 15 from human heart, a member of the T-type Ca2+ channel gene family. Circ Res 16 83, 103-109. 17 18 Eller P, Berjukov S, Wanner S, Huber I, Hering S, Knaus HG, Toth G, Kimball SD & 19 Striessnig J. (2000). High affinity interaction of mibefradil with voltage-gated 20 calcium and sodium channels. Br J Pharmacol 130, 669-677. 21 22 Fry CH, Sui G & Wu C. (2006). T-type Ca2+ channels in non-vascular smooth muscles. 23 Cell Calcium 40, 231-239. 24 25 Garfield RE, Saade G, Buhimschi C, Buhimschi I, Shi L, Shi SQ & Chwalisz K. (1998). 26 Control and assessment of the uterus and cervix during pregnancy and labour. 27 Hum Reprod Update 4, 673-695. 28 29 Gomora JC, Enyeart JA & Enyeart JJ. (1999). Mibefradil potently blocks ATP-activated 30 K(+) channels in adrenal cells. Mol Pharmacol 56, 1192-1197. 31 32 Jones K, Shmygol A, Kupittayanant S & Wray S. (2004). Electrophysiological 33 characterization and functional importance of calcium-activated chloride channel 34 in rat uterine myocytes. Pflugers Arch 448, 36-43. 35 36 Khan RN, Smith SK, Morrison JJ & Ashford ML. (1993). Properties of large37 conductance K+ channels in human myometrium during pregnancy and labour. 38 Proc Biol Sci 251, 9-15. 39 40 Khan RN, Smith SK, Morrison JJ & Ashford ML. (1997). Ca2+ dependence and 41 pharmacology of large-conductance K+ channels in nonlabour and labour human 42 uterine myocytes. Am J Physiol 273, C1721-1731. 43 Downloaded from jp.physoc.org at University of Warwick on July 14, 2008 PAGE - 23 - Kim D, Song I, Keum S, Lee T, Jeong MJ, Kim SS, McEnery 1 MW & Shin HS. (2001). 2 Lack of the burst firing of thalamocortical relay neurons and resistance to absence seizures in mice lacking alpha(1G) T-type Ca(2+) channels. Neuron 31, 35-45. 34 5 Klockner U & Isenberg G. (1985). Action potentials and net membrane currents of 6 isolated smooth muscle cells (urinary bladder of the guinea-pig). Pflugers Arch 405, 329-339. 78 9 Knock GA & Aaronson PI. (1999). Calcium antagonistic properties of the 10 cyclooxygenase-2 inhibitor nimesulide in human myometrial myocytes. Br J 11 Pharmacol 127, 1470-1478. 12 13 Knock GA, Smirnov SV & Aaronson PI. (1999). Voltage-gated K+ currents in freshly 14 isolated myocytes of the pregnant human myometrium. J Physiol 518, 769-781. 15 16 Lee JH, Daud AN, Cribbs LL, Lacerda AE, Pereverzev A, Klockner U, Schneider T & 17 Perez-Reyes E. (1999a). Cloning and expression of a novel member of the low 18 voltage-activated T-type calcium channel family. J Neurosci 19, 1912-1921. 19 20 Lee JH, Gomora JC, Cribbs LL & Perez-Reyes E. (1999b). Nickel block of three cloned 21 T-type calcium channels: low concentrations selectively block alpha1H. Biophys J 22 77, 3034-3042. 23 24 Monteil A, Chemin J, Leuranguer V, Altier C, Mennessier G, Bourinet E, Lory P & 25 Nargeot J. (2000). Specific properties of T-type calcium channels generated by 26 the human alpha 1I subunit. J Biol Chem 275, 16530-16535. 27 28 Moosmang S, Haider N, Bruderl B, Welling A & Hofmann F. (2006). Antihypertensive 29 effects of the putative T-type calcium channel antagonist mibefradil are mediated 30 by the L-type calcium channel Cav1.2. Circ Res 98, 105-110. 31 32 Nebe B, Holzhausen C, Rychly J & Urbaszek W. (2002). Impaired mechanisms of 33 leukocyte adhesion in vitro by the calcium channel antagonist mibefradil. 34 Cardiovasc Drugs Ther 16, 183-193. 35 36 Ohkubo T, Inoue Y, Kawarabayashi T & Kitamura K. (2005a). Identification and 37 electrophysiological characteristics of isoforms of T-type calcium channel 38 Ca(v)3.2 expressed in pregnant human uterus. Cell Physiol Biochem 16, 245-254. 39 40 Ohkubo T, Kawarabayashi T, Inoue Y & Kitamura K. (2005b). Differential expression of 41 L- and T-type calcium channels between longitudinal and circular muscles of the 42 rat myometrium during pregnancy. Gynecol Obstet Invest 59, 80-85. 43 44 Parkington HC, Tonta MA, Brennecke SP & Coleman HA. (1999a). Contractile activity, 45 membrane potential, and cytoplasmic calcium in human uterine smooth muscle in Downloaded from jp.physoc.org at University of Warwick on July 14, 2008 PAGE - 24 - the third trimester of pregnancy and during labour. 1 Am J Obstet Gynecol 181, 1445-1451. 23 4 Parkington HC, Tonta MA, Davies NK, Brennecke SP & Coleman HA. (1999b). 5 Hyperpolarization and slowing of the rate of contraction in human uterus in 6 pregnancy by prostaglandins E2 and f2alpha: involvement of the Na+ pump. J Physiol 514 ( Pt 1), 229-243. 78 9 Perez-Reyes E. (2003). Molecular physiology of low-voltage-activated t-type calcium 10 channels. Physiol Rev 83, 117-161. 11 12 Perez-Reyes E. (2004). Paradoxical Role of T-type Calcium Channels in Coronary 13 Smooth Muscle. Mol Interv 4, 16-18. 14 15 Perez-Reyes E, Cribbs LL, Daud A, Lacerda AE, Barclay J, Williamson MP, Fox M, 16 Rees M & Lee JH. (1998). Molecular characterization of a neuronal low-voltage17 activated T-type calcium channel. Nature 391, 896-900. 18 19 Perez GJ, Toro L, Erulkar SD & Stefani E. (1993). Characterization of large20 conductance, calcium-activated potassium channels from human myometrium. 21 Am J Obstet Gynecol 168, 652-660. 22 23 Viana F, Van den Bosch L, Missiaen L, Vandenberghe W, Droogmans G, Nilius B & 24 Robberecht W. (1997). Mibefradil (Ro 40-5967) blocks multiple types of voltage25 gated calcium channels in cultured rat spinal motoneurones. Cell Calcium 22, 26 299-311. 27 28 Woodcock NA, Taylor CW & Thornton S. (2006). Prostaglandin F(2alpha) increases the 29 sensitivity of the contractile proteins to Ca(2+) in human myometrium. Am J 30 Obstet Gynecol. 31 32 Young RC, Smith LH & McLaren MD. (1993). T-type and L-type calcium currents in 33 freshly dispersed human uterine smooth muscle cells. Am J Obstet Gynecol 169, 34 785-792. 35 36 Young RC & Zhang P. (2005). Inhibition of in vitro contractions of human myometrium 37 by mibefradil, a T-type calcium channel blocker: support for a model using 38 excitation-contraction coupling, and autocrine and paracrine signaling 39 mechanisms. Journal of the Society for Gynecologic Investigation, 12, e7-12. 40 41 Zamponi GW, Bourinet E & Snutch TP. (1996). Nickel block of a family of neuronal 42 calcium channels: subtype- and subunit-dependent action at multiple sites. J 43 Membr Biol 151, 77-90.
URI:	http://wrap.warwick.ac.uk/id/eprint/103