Manpei Kawakami

ATP regulation of ciliary beat frequency in rat tracheal and distal airway epithelium

Ciliary beat frequency (CBF) was measured by video‐optical microscopy in rat tracheal and distal airway ciliary cells using a slice preparation. In tracheal ciliary cells (tracheal slice), ATP or 2‐methylthio ATP (MeSATP) increased CBF, which was inhibited by suramin (100 μm, an inhibitor of purinergic receptor). Ionomycin (5 μm) or thapsigargin (2 μm) increased CBF similarly. Ca2+‐free solution or addition of Ni2+ (1 mm) decreased CBF gradually by approximately 25% and subsequent stimulation with ATP (10 μm) increased CBF transiently. The purinergic agonist experiments demonstrated that ATP increases CBF in tracheal ciliary cells via both P2X and P2Y receptors. ATP increased the intracellular calcium concentration ([Ca2+]i) in tracheal ciliary cells. However, in distal airway ciliary cells (lung slice), ATP did not increase CBF and [Ca2+]i, although a Ca2+‐free solution decreased CBF, and ionomycin (5 μm) or thapsigargin (2 μm) increased it. Moreover, acetylcholine (100 μm) did not increase CBF in distal airway ciliary cells, although it increased CBF in tracheal ciliary cells. Terbutaline (10 μm), a selective β2‐adrenergic agonist, increased CBF in both tracheal and distal airway ciliary cells. These observations suggest that the Ca2+‐mobilization mechanisms via purinergic or muscarinic receptors of the distal airway ciliary cell may be different from those of the tracheal ciliary cell. In conclusion, the CBF increase is differently regulated in the tracheal and distal airway epithelia of the rat.

The synergistic effects of hyperthermia and anticancer drugs on induction of apoptosis

We studied the synergistic effects of hyperthermia and anticancer drugs on induction of apoptosis in lung cancer cells (LK-2 and LU-65A) using in situ end-labeling of DNA, the DNA fragmentation assay, and transmission electron microscopy. A few apoptotic cells were detected only when both cell lines were heated at relatively high temperature (44°C). Moderate numbers of apoptotic cells were observed when both cell lines were incubated with high concentrations (30 or 40 μM) of anticancer drug. Compared with hyperthermia or anticancer drug alone, the combined treatment induced many apoptotic cells in both cell lines, even in the cells treated with lower concentrations (6 or 8 μM) of anticancer drugs following mild hyperthermia (43°C). In regard to kinetics of apoptotic cells induced by treatment, the maximum induction of apoptosis by the combined treatment was higher than that of hyperthermia or anticancer drug alone in both cell lines, although the time of the peak of apoptotic index differed among the three treatments. Therefore, “hyperthermo-chemotherapy” may reduce the required dosage of anticancer drug and decrease the temperature of hyperthermia on induction of apoptosis.

Hypo‐osmotic potentiation of acetylcholine‐stimulated ciliary beat frequency through ATP release in rat tracheal ciliary cells

The ciliary beat frequency (CBF) of rat tracheal ciliary cells in a slice preparation was measured using video‐enhanced contrast (VEC) microscopy. Acetylcholine (ACh) increased CBF mediated via intracellular Ca2+ concentration ([Ca2+]i) in a dose‐dependent manner. An adequate hypo‐osmotic stress (−40 mosm) potentiated ACh‐stimulated CBF increase in tracheal ciliary cells and shifted the ACh dose–response curve to the left (lower concentration side). This potentiation was independent of hypo‐osmotic stresses applied ranging from −20 mosM to −90 mosM. A hypo‐osmotic stress induces ATP release in many cell types. The present study demonstrated that suramin (an inhibitor of purinergic receptors) and apyrase (an ATPase/ADPase) eliminate the hypo‐osmotic potentiation of ACh‐stimulated CBF increase and that ATP increased [Ca2+]i and CBF, as well as potentiating ACh‐stimulated rises in [Ca2+]i and CBF increase. Moreover, the apical surface of tracheal ciliary cells were stained immunopositive for the P2X4 purinergic receptor. A hypo‐osmotic stress (−40 mosM) transiently increased [Ca2+]i and potentiated the ACh‐stimulated [Ca2+]i increase. The hypo‐osmotic potentiation of ACh‐stimulated CBF increase was not detected under Ca2+‐free conditions. These observations suggest that a hypo‐osmotic stress stimulates ATP release from the trachea. The released ATP may induce further increases in [Ca2+]i and CBF in ACh‐stimulated tracheal ciliary cells, which may be mediated by purinergic receptors, such as P2X4.

Idiopathic Mediastinal Fibrosis:Report of a Case

We report herein the case of a 28-year-old woman who presented with a mediastinal mass, subsequently confirmed to be idiopathic mediastinal fibrosis. Preoperative chest computed tomography (CT) showed a noncalcified mediastinal mass and surgery was performed to exclude malignancy. The mass was hard and dense, involved the left phrenic nerve, vagus nerve, and left upper lobe, and surrounded the subclavian artery, subclavian vein, superior vena cava, and left pulmonary artery. Pathologic examination showed the findings of mediastinal fibrosis and the mass was partially excised. Postoperative medical treatment was performed with prednisolone and tranilast, and a 3-year follow-up has not demonstrated any complications.

Primary hemangiopericytoma of the trachea

A 28-year-old man arrived at our hospital complaining of severe dyspnea. Bronchoscopic findings demonstrated that a tumor was located approximately 4 cm distant from the vocal cord, occupying most of the tracheal lumen. To urgently relieve the dyspnea, some parts of the tumor were cauterized with the neodymium:yttrium-aluminum garnet laser. Histopathologic examination of the cauterized specimen revealed malignant hemangiopericytoma. During the operation, the tumor was resected en bloc with a tracheal segment containing four tracheal cartilages. The patients postoperative course was uneventful with no evidence of recurrence 1 year after the operation.