title: Impaired platelet-derived growth factor receptor expression and function in cultured lower esophageal sphincter circular smooth muscle cells from W/W(v) mutant mice.
abstract: We have previously demonstrated that lower esophageal sphincter (LES) circular smooth muscle (CSM) is functionally impaired in W/W(v) mutant mice that lack interstitial cells of Cajal, and speculated that this could be due to altered smooth muscle differentiation. Platelet-derived growth factor (PDGF) is involved in the maturation and differentiation of smooth muscle. To determine whether PDGF expression and (or) function is altered in W/W(v) mutant mice, PDGF-Rβ expression was measured using RT-PCR, qPCR, and immunocytochemistry, and Ca(2+) imaging and perforated patch clamp recordings performed in isolated LES CSM cells. RT-PCR and immunocytochemistry showed significantly reduced PDGF-Rβ expression in the LES from mutant as opposed to wild-type mice. Quantitative comparison of CSM cell numbers in histological specimens revealed a significantly increased average cell size in the mutant tissue. The specific PDGF-Rβ ligand, PDGF-BB, caused a significant increase in intracellular Ca(2+) in cells from the wild-type mice compared with the mutants. Using a ramp protocol, PDGF-BB caused a 2-fold increase in outward K(+) currents in cells from the wild-type mice, whereas no significant increase was measured in the cells from the mutants. We conclude that the expression and function of PDGF-Rβ in LES CSM from W/W(v) mice is impaired, providing further evidence that LES CSM is abnormal in W/W(v) mutants.
authors.affiliation: a Gastrointestinal Disease Research Unit, Kingston General Hospital, 76 Stuart Street, Kingston ON K7L 2V7, Canada.
authors.forename: Francisco
authors.initials: F
authors.lastname: Bautista-Cruz
authors.forename: Dileep G
authors.initials: DG
authors.lastname: Nair
authors.forename: Sandra
authors.initials: S
authors.lastname: Lourenssen
authors.forename: David V
authors.initials: DV
authors.lastname: Miller
authors.forename: Michael G
authors.initials: MG
authors.lastname: Blennerhassett
authors.forename: William G
authors.initials: WG
authors.lastname: Paterson
mesh_terms: D000818:Animals; D000077214:Becaplermin; D002118:Calcium / Q000378:metabolism; D048429:Cell Size; D002478:Cells, Cultured; D003106:Colon / Q000502:physiology; D049630:Esophageal Sphincter, Lower / Q000166:cytology / Q000378:metabolism*; D005260:Female; D008297:Male; D008817:Mice, Mutant Strains; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics / Q000378:metabolism*
chemical_list: D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D020797:Receptor, Platelet-Derived Growth Factor beta; D011188:Potassium; D002118:Calcium