title: Morphological and functional changes in cell junctions during secretory stimulation in the perfused rat submandibular gland.
abstract: To examine the influence of cholinergic and beta-adrenergic agents on paracellular transport, we applied confocal microscopy and freeze-fracture to the isolated, perfused submandibular gland of the rat. By confocal microscopy, perfusion of lucifer yellow through an arterial catheter, revealed a bright fluorescence in the basolateral spaces of acini, but not in the intercellular canaliculi. However, addition of isoproterenol on carbachol stimulation, induced lucifer yellow fluorescence in intercellular canaliculi. This finding indicates that isoproterenol is capable of opening the paracellular route. The tight junction strands surrounding intercellular canaliculi were visualized using freeze replicas. Fixation was carried out both by vascular perfusion with Karnovsky's solution and by metal contact rapid freezing with liquid helium. In the chemically-fixed specimens, the strand particles of tight junctions formed 2-5 lines at the P-face along most of the apical portion at rest. With carbachol/isoproterenol stimulation, the strand particles rearranged with free ends and terminal loops. In the rapidly frozen specimens, the strand particles were arranged more irregularly even in the resting state. The meshwork of strands became more disheveled and interrupted during carbachol/ isoproterenol stimulation. The present findings led us to conclude that: 1) the beta-adrenergic agent, isoproterenol, can open the paracellular transport. 2) in the rapidly frozen specimen, the tight junction strand particles are arranged roughly and become disheveled and interrupted during stimulation by carbachol/isoproterenol. These findings may be related to rearrangement of subcellular structures, especially of the actin filament network.
authors.affiliation: Pathology, Oral Health Science Center, Tokyo Dental College, Chiba, Japan. sada@tdc.ac.jp
authors.forename: Sadamitsu
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Masataka
authors.initials: M
authors.lastname: Murakami
authors.forename: Toku
authors.initials: T
authors.lastname: Kanaseki
authors.forename: Satoko
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Miwako
authors.initials: M
authors.lastname: Matsuki
authors.forename: Masaki
authors.initials: M
authors.lastname: Shimono
authors.forename: Akihisa
authors.initials: A
authors.lastname: Segawa
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D005404:Fixatives; D005614:Freeze Fracturing; D005615:Freezing; D066298:In Vitro Techniques; D007365:Intercellular Junctions / Q000502:physiology* / Q000648:ultrastructure*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D018613:Microscopy, Confocal; D010477:Perfusion; D051381:Rats / Q000033:anatomy & histology* / Q000502:physiology*; D017208:Rats, Wistar; D013363:Submandibular Gland / Q000033:anatomy & histology* / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors
chemical_list: D000318:Adrenergic beta-Agonists; D018679:Cholinergic Agonists; D005404:Fixatives; D002217:Carbachol; D007545:Isoproterenol