title: Characterisation of K+ channels in human fetoplacental vascular smooth muscle cells.
abstract: Adequate blood flow through placental chorionic plate resistance arteries (CPAs) is necessary for oxygen and nutrient transfer to the fetus and a successful pregnancy. In non-placental vascular smooth muscle cells (SMCs), K(+) channels regulate contraction, vascular tone and blood flow. Previous studies showed that K(+) channel modulators alter CPA tone, but did not distinguish between effects on K(+) channels in endothelial cells and SMCs. In this study, we developed a preparation of freshly isolated CPASMCs of normal pregnancy and investigated K(+) channel expression and function. CPASMCs were isolated from normal human term placentas using enzymatic digestion. Purity and phenotype was confirmed with immunocytochemistry. Whole-cell patch clamp was used to assess K(+) channel currents, and mRNA and protein expression was determined in intact CPAs and isolated SMCs with RT-PCR and immunostaining. Isolated SMCs expressed α-actin but not CD31, a marker of endothelial cells. CPASMCs and intact CPAs expressed h-caldesmon and non-muscle myosin heavy chain-2; phenotypic markers of contractile and synthetic SMCs respectively. Whole-cell currents were inhibited by 4-AP, TEA, charybdotoxin and iberiotoxin implicating functional K(v) and BK(Ca) channels. 1-EBIO enhanced whole cell currents which were abolished by TRAM-34 and reduced by apamin indicating activation of IK(Ca) and SK(Ca) respectively. BK(Ca), IK(Ca) and SK(Ca)3 mRNA and/or protein were expressed in CPASMCs and intact CPAs. This study provides the first direct evidence for functional K(v), BK(Ca,) IK(Ca) and SK(Ca) channels in CPASMCs. These cells display a mixed phenotype implicating a dual role for CPASMCs in controlling both fetoplacental vascular resistance and vasculogenesis.
authors: Maternal and Fetal Health Research Centre, Institute of Human Development, University of Manchester, St. Mary's Hospital, Manchester, United Kingdom. melissa.brereton@dpag.ox.ac.uk
authors: Melissa F
authors: MF
authors: Brereton
authors: Mark
authors: M
authors: Wareing
authors: Rebecca L
authors: RL
authors: Jones
authors: Susan L
authors: SL
authors: Greenwood
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002823:Chorion / Q000098:blood supply / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D005333:Fetus; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010920:Placenta / Q000098:blood supply / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D000199:Actins; D002148:Calmodulin-Binding Proteins; D026902:Potassium Channel Blockers; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D018995:Myosin Heavy Chains; D011188:Potassium; D002118:Calcium