title: Endothelial Tight Junctions Are Opened in Cholinergic-Evoked Salivation In Vivo.
abstract: Blood vessels provide the original supplies for the formation of primary saliva, which is regulated by the tight junctions (TJs) between endothelial cells. Previous studies have shown that blood flow increases with vasodilatation during cholinergic-evoked salivation. However, changes in vascular paracellular permeability and the role of endothelial TJs in salivation are unknown. Here, we established an in vivo paracellular permeability detection system and observed that the endothelial TJs were permeable to 4-kDa fluorescein isothiocyanate (FITC)-dextran while impermeable to 40- and 70-kDa FITC-dextran under an unstimulated condition in mouse submandibular glands (SMGs). Pilocarpine increased the flux of 4- and 40-kDa FITC-dextran out of blood vessels but did not affect 70-kDa FITC-dextran. Claudin 5, a TJ protein specifically localized in salivary endothelial cells, was redistributed from the apicolateral membranes to the lateral and basolateral membranes and cytoplasm in cholinergic-stimulated mouse SMGs and freshly cultured human SMG tissues. In the transplanted SMGs from epiphora patients, we found that claudin 5 was present in the basolateral membranes and cytoplasm, instead of the apical region in control SMGs. Moreover, the level of phospho-myosin light chain 2 increased within the blood vessels of the pilocarpine-stimulated mouse SMGs and transplanted human SMGs, while the downstream molecule F-actin was reorganized in the endothelial cells of the transplanted human SMGs. Taken together, our findings provide direct visual evidence that the opening of endothelial TJs and the redistribution of claudin 5 are essential events contributing to cholinergic-evoked salivation, thus enriching our understanding of the secretory mechanisms that link blood flow to primary saliva formation by regulating the endothelial paracellular permeability.
authors.affiliation: 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China.
authors.forename: X
authors.initials: X
authors.lastname: Cong
authors.affiliation: 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: 2 Center of Medical and Health Analysis, Peking University Health Science Center, Beijing, P.R. China.
authors.forename: Q H
authors.initials: QH
authors.lastname: He
authors.affiliation: 3 Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, P.R. China.
authors.forename: T
authors.initials: T
authors.lastname: Wei
authors.affiliation: 3 Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, P.R. China.
authors.forename: X M
authors.initials: XM
authors.lastname: Zhang
authors.affiliation: 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China.
authors.forename: J Z
authors.initials: JZ
authors.lastname: Zhang
authors.affiliation: 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China.
authors.forename: R L
authors.initials: RL
authors.lastname: Xiang
authors.affiliation: 3 Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, P.R. China.
authors.forename: G Y
authors.initials: GY
authors.lastname: Yu
authors.affiliation: 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China.
authors.forename: L L
authors.initials: LL
authors.lastname: Wu
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D024722:Cardiac Myosins / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects*; D062507:Claudin-5 / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D018994:Myosin Light Chains / Q000378:metabolism; D010862:Pilocarpine / Q000494:pharmacology*; D012472:Salivation / Q000502:physiology*; D015398:Signal Transduction; D013363:Submandibular Gland / Q000378:metabolism / Q000502:physiology*; D019108:Tight Junctions / Q000378:metabolism / Q000502:physiology*
chemical_list: D000199:Actins; D062507:Claudin-5; D003911:Dextrans; D018994:Myosin Light Chains; C015219:fluorescein isothiocyanate dextran; C107184:myosin light chain 2; D010862:Pilocarpine; D024722:Cardiac Myosins; D016650:Fluorescein-5-isothiocyanate
keywords: F-actin; claudin 5; endothelium; myosin light chains; secretion; submandibular gland