Tachykinins induce a [Ca2+]i rise in the acinar cells of feline tracheal submucosal gland

Abstract The intracellular Ca + concentration ([Ca 2+ ] i ) of acinar cells of isolated submucosal glands from trachea was measured using a fluorescent dye, Fura-2. Neurokinin A (NK-A) produced a sustained rise in [Ca 2+ ] i in a dose-dependent manner, reaching a response of 500 to 600% of the prior baseline value at 10 −6 or 10 −5 M, and the NK-A evoked [Ca 2+ ] i was significantly higher than that by substance P (SP) at similar concentrations. NK-B did not induce significant increases in [Ca 2+ ] i . In a Ca 2+ -free solution. NK-A produced a transient rise in [Ca 2+ ] i , which returned to the baseline within 3 min. Mucus glycoprotein (MGP) secretion, estimated by measuring trichloroacetic-acid (TCA) precipitable glycoconjugates, was stimulated by NK-A or SP. These findings indicate that tachykinins produce a rise in [Ca 2+ ] i by both entry from the extracellular solution and release from intracellular storage, probably by NK-2 receptor stimulation, and stimulate MGP secretion from airway submucosal glands.