Yasunori Kakuta

Effect of artificial surfactant on ciliary beat frequency in guinea pig trachea

This study defines the effect of artificial surfactant on ciliary beat frequency. We employed guinea pig tracheal rings and a photomultiplier which allows in vitro measurement of ciliary beat frequency. The beat frequency without surfactant decreased continuously while surfactant caused a relative increase in beat frequency. The difference between the relative beat frequency in the presence and absence of surfactant was significant. The effect of surfactant was dose dependent. Fifteen minute treatments with 2 mM hydrogen peroxide reduced the beat frequency. The reduction partially recovered in the absence of surfactant. In contrast, surfactant markedly accelerated the recovery of the beat frequency. Surfactant did not influence the effect of terbutaline (a beta 2-adrenergic agonist) on beat frequency. These results indicate that artificial surfactant can, in some circumstances, promote ciliary beat frequency. This concept is important to the clearance mechanism of the airways, and its application to some pathophysiological states such as chronic bronchitis and bronchial asthma should be considered.

Characteristics of the increase in plasma brain natriuretic peptide level in left ventricular systolic dysfunction, associated with muscular dystrophy in comparison with idiopathic dilated cardiomyopathy

To determine whether the plasma brain natriuretic peptide level increases differentially in muscular dystrophy and idiopathic dilated cardiomyopathy, we investigated the plasma brain natriuretic peptide level and echocardiographic parameters in patients with similarly low left ventricular ejection fraction. The plasma brain natriuretic peptide level was lower, and the left ventricular end-diastolic diameter was shorter in the patients with muscular dystrophy than in those with idiopathic dilated cardiomyopathy. The correlation between the plasma brain natriuretic peptide and left ventricular ejection fraction was shifted downward in the patients with muscular dystrophy compared with those with idiopathic dilated cardiomyopathy. Those between the brain natriuretic peptide and left ventricular end-diastolic diameter were superimposable, although the data from the muscular dystrophy patients were located at the shorter left ventricular end-diastolic diameter side. The plasma brain natriuretic peptide level may differentially increase in the two diseases with similar left ventricular systolic dysfunction. Differences in the left ventricular distension and in the physical activity might explain at least partially the different plasma brain natriuretic peptide levels.

K channels of human alveolar macrophages

The activation of macrophages has been reported to be associated with Ca-activated K permeability change. In order to study this permeability change in human alveolar macrophages, we examined alveolar macrophages electrophysiologically at a single channel level. We observed two types of Ca-activated K channel currents having conductances of 218 +/- 2 and 32 +/- 0.6 picosiemens in symmetrical 154 mmol/L KCl solutions. The characteristics, such as voltage dependency and Ca sensitivity, as well as channel conductance, were different between these two types of channel currents. Quinine (a blocker of Ca-activated K conductance), 0.5 mmol/L, reduced these channel currents by 45 +/- 8% and 31 +/- 8%. Quinine, 0.5 mmol/L, also inhibited chemiluminescence and leukotriene B4 release by 82 +/- 6 to 88 +/- 3% and 88 +/- 2%, respectively. These results suggest the presence of two types of Ca-activated K channels, which may be related to the release of inflammatory mediators from human alveolar macrophages.

Effect of ketotifen on human alveolar macrophages

In order to examine the possibility of human alveolar macrophages being an effector site of an antiasthmatic drug, we studied the effect of ketotifen on chemiluminescence and Ca-activated K conductance at single channel level because they are associated with the activation of macrophages. Peak chemiluminescence response, induced by a single concentration of phorbol myristate acetate (0.5 micrograms/ml), was inhibited by 28 +/- 3, 51 +/- 8, and 76 +/- 7% by ketotifen concentrations of 0.02, 0.12, and 0.24 mmol/L, respectively. The inhibition of chemiluminescence by ketotifen concentrations of 0.12 and 0.24 mmol/L was also observed in macrophages stimulated with zymosan activated serum (54 +/- 7 and 80 +/- 6%, respectively). Moreover, ketotifen, 0.24 mmol/L, inhibited Ca-activated K channel currents by 44 +/- 7% (large currents) and 48 +/- 13% (small currents). These results may explain, at least partly, antiasthmatic effects of ketotifen.

Effects of Qing-Fei-Tang (Seihai-to) and Baicalein, Its Main Component Flavonoid, on Lucigenin-Dependent Chemiluminescence and Leukotriene-Dependence Chemiluminescence and Leukotriene B4 Synthesis of Human Alveolar Macrophages

A traditional Chinese remedy, Qing-Fei-Tang (Seihai-to, T90), has been used for treatment of chronic respiratory diseases with long-lasting cough and sputum, e.g. chronic bronchitis. We examined the effect of T90 and its main component flavonoid, baicalein, on the lucigenin-dependent chemiluminescence (CL) and leukotriene B4 (LTB4) synthesis of human alveolar macrophages (AM). AM were obtained by bronchoalveolar lavage from patients with various respiratory diseases, including sarcoidosis, idiopathic pulmonary fibrosis, bronchial asthma, chronic bronchitis and lung cancer. CL were observed by stimulating 1 x 10(5) AM with phorbol myristate acetate in the presence of lucigenin. LTB4 were generated by incubating 1 x 10(6)/ml AM with Ca ionophore A23187 for 30 min and determined by reverse phase high performance liquid chromatography and radioimmunoassay. T90 (0.2-2.0 mg/ml) and baicalein (0.1-100 microM) inhibited both CL and LTB4 production of AM in a dose-dependent fashion. These inhibitory effects were not due to cytotoxic effects of the procedure because neither 2 mg/ml T90 nor 100 M baicalein affected the viability of AM nor lactate dehydrogenase release from AM. These results suggest that T90 exerts its effect on inflammatory lung diseases through the anti-inflammatory action, i.e. inhibiting the oxidative and arachidonate metabolism of local inflammatory lung cells.

Effect of Ca2+ on the ciliary beat frequency of skinned dog tracheal epithelium.

Beat frequency of dog tracheal ciliated epithelium was measured using a profile projector and a photomultiplier. The preparation, treated with 50 micrograms/ml of saponin for 15 min, lost osmotic behavior and the ciliary beat came to depend on externally applied MgATP2- indicating that ciliated epithelium is skinned with saponin. Beat frequency of skinned cilia did not increase with Ca2+ in 0.1 mM MgATP2- with no ATP-regenerating system. Under 4 mM Mg ATP2- the beat frequency increased with an increase in Ca2+ from 0.3 to 10 microM, although a marked beat continued in the virtual absence of Ca2+ sensitivity and maximum beat frequency increased with the addition of 2.4 microM calmodulin. The effect of calmodulin inhibitor (W-7) on skinned preparations was somewhat weaker than that on intact ones. We concluded that Ca2+, within the physiological range of concentrations, directly activated the ciliary proteins and increased the ciliary beat frequency. The addition of calmodulin augments the effect of Ca2+ but the basal beat frequency is not Ca2+ dependent.

Effects of ATP and related compounds on the Ca-induced Ca release mechanism of theXenopus SR

The effects of ATP and related compounds on the Ca2+ release mechanism of the sarcoplasmic reticulum (SR) was studied by using skinned skeletal muscle fibers ofXenopus laevis. ATP evoked marked Ca2+ release at very low level of Mg2+. β, γ-Methylene analogue of ATP was almost as effective as ATP, which suggests Ca2+ release evoked by ATP is elicited without ATP hydrolysis. ADP and AMP also evoked Ca2+ release from the SR, but the effect of them became gradually weaker than that of ATP as the number of phosphates decreased. CTP, UTP and ITP were less potent than ATP. Adenosine also evoked more effective Ca2+ release than inosine. The compounds with adenine base, therefore, seem to elicit more potent Ca2+ release than those which have the same number of phosphates but do not consist of adenine base. AMP and Ca2+ ion evoked Ca2+ release synergistically, and the Ca2+ release responses evoked by ATP and related compounds showed the same pharmacological characteristics as Ca-induced Ca release. So, these Ca2+ release responses are construed as the manifestation of the same mechanism as Ca-induced Ca release. Effective concentration range of ATP and the effect of pyrophosphate on Ca2+ release evoked by ATP suggest that neither the high affinity ATP catalytic site of (Ca2++Mg2+) ATPase of the SR nor the low affinity ATP binding site, reported by Dupont (1977), is implicated in the enhancement of these Ca2+ release responses from the SR.