TACHYKININS INDUCE A [CA2-CELLS OF FELINE TRACHEAL SUBMUCOSAL GLAND(]I RISE IN THE ACINAR)

The intracellular Ca2+ concentration ([Ca2+](i)) of acinar cells of is olated submucosal glands from trachea was measured using a fluorescent dye, Fura-2. Neurokinin A (NK-A) produced a sustained rise in [Ca2+]( i) in a dose-dependent manner, reaching a response of 500 to 600% of t he 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 simil ar concentrations. NK-B did not induce significant increases in [Ca2+] (i). In a Ca2+-free solution, NK-A produced a transient rise in [Ca2+] (i), which returned to the baseline within 3 min. Mucus glycoprotein ( MGP) secretion, estimated by measuring trichloroacetic-acid (TCA) prec ipitable glycoconjugates, was stimulated by NK-A or SP. These findings indicate that tachykinins produce a rise in [Ca2+](i) by both entry f rom the extracellular solution and release from intracellular storage, probably by NK-2 receptor stimulation, and stimulate MGP secretion fr om airway submucosal glands.