タキキニンのウサギ気管粘膜繊毛活性への影響

抄録

Recent studies have revealed that abundant neuropeptide positive fibers exist even in the epithelium, suggesting that neuropeptides released from these fibers by various stimuli take part in epithelial responses in allergy and inflammation. The aim of this study was to clarify the effect of tachykinin on tracheal mucosal ciliated cells.
Mucosal specimens were obtained from the trachea of a rabbit sacrificed following nembutal injection into the peritoneum. The mucosal specimens were cut into 4×4mm pieces and cultured with RPMI 1640 in a 100% and humidified thermoregulated chamber at 37°C under 5% CO₂ and 95% air. The mucosal surface was observed on a TV monitor at a magnification of approximately 2, 500× and was recorded simultaneously on video tape. The ciliary activity was photoelectorically measured on a TV screen.
Substance P (SP) and neurokinin A (NKA) induced ciliostimulations in a concentration-dependent manner showing a peak 1 to 2 minutes after exposure. Capsaicin, a potent SP liberator, showed a similar ciliostimulation, also in a concentration dependent manner. These ciliostimulations were completely blocked by pretreatment with a tachykinin-receptor antagonist. Thiorphan prolonged the duration of the ciliostimulation induced by SP and/or NKA, while it did not affect its maximum level. SP- and NKA-induced ciliostimulations were also completely blocked by verapamil, but not by propranolol or indomethacin. These results indicate that SP and NKA promote ciliary activity via the calcium channel, thereby increasing calcium concentration in the cytoplasm of ciliated cells.
Leukotriene C₄ induced mild temporary ciliostimulation, but pretreatment with a tachykinin-receptor antagonist completely blocked this phenomenon, suggesting neuropeptide-mediated ciliostimulation.