title: Characteristics of neurokinin A-induced salivary fluid secretion in perfused rat submandibular gland.
abstract: Tachykinins such as neurokinin A (NKA) and substance P have been demonstrated to induce salivary fluid secretion in vivo. However, characteristics of salivary fluid secretion induced by tachykinins in salivary glands have not been well elucidated. In this study, the effects of the tachykinin NKA on salivary fluid secretion were investigated in isolated, perfused rat submandibular gland. NKA provoked salivary fluid secretion, which consisted of transient and sustained phases, in a dose-dependent manner. In fura-2-loaded dispersed cells of the rat submandibular gland, the doses of NKA in which induced salivary fluid secretion caused an increase in intracellular Ca(2+) concentration. When Ca(2+) was removed from the perfusate to examine the effect of Ca(2+) mobilization on NKA-induced fluid secretion, only the transient salivary fluid secretion occurred. When the gland was perfused with the Ca(2+)-free perfusate containing the intracellular Ca(2+) chelator BAPTA-AM, NKA failed to induce salivary fluid secretion. NKA also induced an increase in oxygen consumption, but which was reduced by the removal of Ca(2+) from perfusate. Salivary fluid is secreted via transcellular and paracellular pathways in acinar cells of salivary glands. To examine the contribution of paracellular pathway to NKA-induced salivary fluid secretion, the glands were perfused with a perfusate containing Lucifer yellow (LY), a cellular impermeable substance, and then were stimulated with NKA, which provoked secretion of LY in the saliva. These results suggest that the NKA-induced salivary fluid secretion is Ca(2+)-dependent and that the paracellular pathway contributes to the secretion.
authors.affiliation: Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan.
authors.forename: Bing
authors.initials: B
authors.lastname: Qi
authors.forename: Takanori
authors.initials: T
authors.lastname: Narita
authors.forename: Keitaro
authors.initials: K
authors.lastname: Satoh
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Guo
authors.forename: Osamu
authors.initials: O
authors.lastname: Katsumata-Kato
authors.forename: Masataka
authors.initials: M
authors.lastname: Murakami
authors.forename: Junko
authors.initials: J
authors.lastname: Fujita-Yoshigaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sugiya
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D008297:Male; D015288:Neurokinin A / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000187:drug effects; D012463:Saliva / Q000737:chemistry / Q000378:metabolism*; D012472:Salivation / Q000187:drug effects*; D013268:Stimulation, Chemical; D013363:Submandibular Gland / Q000187:drug effects / Q000378:metabolism*
chemical_list: D018377:Neurotransmitter Agents; D018040:Receptors, Neurokinin-1; D015288:Neurokinin A; D002118:Calcium