Biomedical subjects

J Tamaoki

Publications and source records attributed to J Tamaoki.

At least 145 records · Page 8Linked to original sources

PubMed1992

Prostaglandin D2 increases Cl secretion across canine tracheal epithelium through cyclo-oxygenase stimulation and cAMP production.

Prostaglandin (PG) D2 is one cyclo-oxygenase product of arachidonic acid metabolites that may play a role in the pathogenesis of asthma. To determine the effect of PGD2 on ion transport by airway epithelium and its mechanism of action, we measured bioelectric properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. PGD2 (10(-7) M) increased short-circuit current (Isc) from 5.5 +/- 1.2 to 14.1 +/- 2.9 microA cm-2 (means +/- SE, P less than 0.01) when added to the mucosal solution, and to 22.2 +/- 3.8 microA cm-2 (P less than 0.001) when added to the submucosal solution, an effect that was accompanied by the corresponding increases in transepithelial potential difference and conductance. These effects were dose-dependent. The PGD2-induced increase in Isc was not altered by preincubation of cells with autonomic antagonists (phentolamine, propranolol, atropine), the lipoxygenase inhibitor AA-861, the protein kinase C inhibitor H-7, or the Na channel blocker amiloride, but it was inhibited by each of indomethacin, piroxicam, the Cl channel blocker diphenylamine-2-carboxylate, the Cl transport inhibitor furosemide, and Cl-free medium. Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels were dose-dependently increased by PGD2. These results suggest that PGD2 may selectively stimulate airway epithelial Cl secretion via cyclo-oxygenase- and cAMP-dependent pathway.

Animals↗

PubMed1992

Non-opioid-dependent inhibitory action of loperamide on cholinergic neurotransmission in canine isolated bronchial smooth muscle.

The effect of loperamide on cholinergic neurotransmission in canine bronchial smooth muscle was studied under isometric conditions in-vitro. Addition of loperamide decreased contractile responses to electrical field stimulation in a dose-dependent fashion, the maximal decrease from the control response and the IC50 value being 65.4 +/- 5.9% and 1.5 microM, respectively. In contrast, loperamide was without effect on the responses to exogenously administered acetylcholine. The inhibitory effect of loperamide was not altered by pre-incubation of tissues with propanol, 6-hydroxydopamine, bicuculline, or naloxone. These results suggest that loperamide attenuates the neurally mediated airway contraction probably by inhibiting acetylcholine release from cholinergic nerve terminals through a non-opioid-dependent mechanism.

Animals↗

PubMed1992

Stimulation of Cl secretion by lactoferrin across canine airway epithelial cells in culture.

To investigate the effect of lactoferrin, an iron-binding glycoprotein in the respiratory tract, on ion transport function of airway epithelial cells, we measured bioelectric properties of canine cultured tracheal epithelium by Ussing's short-circuit technique. Addition of lactoferrin (60 micrograms/ml) to the mucosal side of epithelial sheet increased the short-circuit current (Isc) from 4.8 +/- 0.8 to 7.5 +/- 1.1 microA/cm2, and the submucosal addition likewise increased Isc from 3.8 +/- 0.6 to 5.6 +/- 0.7 microA/cm2 (p < 0.001, in each case). This effect was concentration dependent. The lactoferrin-induced increase in Isc was not altered by amiloride, indomethacin, or propranolol but was abolished by diphenylamine-2-carboxylate or substitution of Cl with iodide in the medium. Intracellular cyclic AMP levels were not increased by lactoferrin. These results suggest that lactoferrin may selectively stimulate Cl secretion across the airway mucosa, an effect that may not be dependent on prostaglandins, beta-adrenergic receptor or intracellular cyclic AMP.

Animals↗

PubMed1992

Effect of indomethacin on bronchorrhea in patients with chronic bronchitis, diffuse panbronchiolitis, or bronchiectasis.

Excessive production of sputum is one of the major symptoms in patients with chronic airway diseases. Because endogenous prostaglandins may play a role in the regulation of airway secretions, blockade of cyclooxygenase pathway with indomethacin could decrease respiratory tract fluid and mucus by inhibiting Cl secretion and glandular secretion and by enhancing Na absorption across airway mucosa. To test this hypothesis, we studied the effect of inhaled indomethacin on bronchorrhea in patients with chronic bronchitis, diffuse panbronchiolitis, and bronchiectasis in a double-blind, placebo-controlled fashion. Patients who inhaled 2 ml of indomethacin (1.2 micrograms/ml) three times a day for 14 days showed a decrease in the amount of sputum, from 189 +/- 19 to 95 +/- 21 g/day (p less than 0.001) and an increase in the solid component of sputum without alterations in parameters of systemic inflammatory responses. Although pulmonary function remained unchanged, perceived dyspnea was improved so that Borg's ratio scale was decreased from 7.1 +/- 0.5 to 4.5 +/- 0.4 (p less than 0.01). Adverse effects, including hypotension and bronchoconstriction, were not observed. The reduction of sputum was accompanied by a significant decrease in the concentrations of prostaglandin (PG)E2, PGF2 alpha, thromboxane B2, and 6-oxo-PGF1 alpha in the sputum. Thus, indomethacin inhalation may be of value in reducing bronchorrhea sputum, probably through the inhibition of PG-dependent airway secretions.

Adult↗

PubMed1992

Angiotensin II-1 receptor-mediated Cl secretion by canine tracheal epithelium.

To elucidate the effect of angiotensin II (AII) on ion transport function of airway epithelium, we studied the bioelectrical properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. Addition of AII to submucosal solution in Ussing chambers increased the short-circuit current (ISC) in a dose-dependent fashion, the maximal increase from the baseline value and the concentration required to produce a half-maximal effect being 5.2 +/- 0.5 microA/cm2 (p < 0.001) and 10(-6) M, respectively. In contrast, mucosal AII had little effect. The AII-induced increase in ISC was not altered by the AII-2 receptor antagonist EXP655 but was depressed by the AII-1 receptor antagonist DuP 753. Diphenylamine-2-carboxylate, Cl-free medium, indomethacin, the phospholipase A2 inhibitor mepacrine, and the methyltransferase inhibitor 3-deazaadenosine reduced the change in ISC, whereas amiloride and the lipoxygenase inhibitor AA-861 did not. Addition of AII to the submucosal but not the mucosal side increased the release of prostaglandin E2, an effect that was abolished by DuP 753. These results suggest that AII may interact with the submucosal AII-1 receptor and stimulate Cl secretion across tracheal epithelium through the mobilization of arachidonic acid and the release of prostaglandin E2.

Angiotensin II↗

PubMed1992

Stimulation of Na absorption by the antiasthmatic kampo drug Saiboku-to in cultured airway epithelium.

To study the effect of the Kampo drug Saiboku-to (TJ-96) on ion transport function of airway epithelial cells, we studied bioelectric properties of cultured tracheal epithelium from dogs under short-circuit conditions in vitro. Addition of TJ-96 (1 mg/ml) to the mucosal solution of the Ussing chamber increased the epithelial short-circuit current (SCC) from 6.5 +/- 0.7 to 11.4 +/- 1.6 microA/cm2 (P less than 0.001). This effect was dose-dependent, with the maximal increase from the baseline value and the concentration required to produce a half-maximal effect (EC50) being 70.5 +/- 12.6% (P less than 0.001) and 3 micrograms/ml, respectively; and there were corresponding increases in transepithelial potential difference and cell conductance. Submucosal addition of TJ-96 likewise increased SCC, although the magnitude of the response was smaller as compared with the response to the mucosal addition. The TJ-96-induced increase in SCC was not affected by diphenylamine-2-carboxylate or furosemide but abolished by amiloride. Intracellular cyclic AMP levels were dose-dependently increased by TJ-96. These results indicate that TJ-96 may selectively stimulate Na absorption across the tracheal epithelium, probably through intracellular accumulation of cyclic AMP.

Animals↗

PubMed1992

[Effects of angiotensin peptides on airway epithelial ion transport and its modulation by angiotensin converting enzyme].

To study the effects of angiotensin (ANG) peptides on airway epithelial ion transport function, we evaluated the bioelectric properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. Addition of ANG I, II and II dose-dependently increased short-circuit current (Isc) and transepithelial potential difference, an effect that was more pronounced with addition to the submucosal solution than to the mucosal solution, with rank order of potency of ANG II greater than or equal to ANG II much greater than ANG I. The ANG-induced increase in Isc was not altered by the Na channel blocker amiloride, but was greatly reduced by the CI channel blocker diphenylamine-2-carboxylate and Cl-free medium. The response of Isc to ANG I was reduced by MK422, an angiotensin converting enzyme inhibitor, in a dose-dependent fashion. These results suggest that ANG II and III selectively stimulate Cl secretion across airway epithelium and that ANG I may exert its effect after its conversion to ANG II by angiotensin converting enzyme.

Angiotensin I↗

PubMed1992

Effects of angiotensin peptides on cholinergic neurotransmission in rabbit tracheal smooth muscle.

To determine the effects of angiotensins I, II, and III (A I, A II, and A III) on airway smooth muscle functions, we studied isolated tracheal segments from rabbits under isometric conditions in vitro. Addition of A II and A III but not A I potentiated the contractile response to electrical field stimulation (EFS) at 5 Hz in a dose-dependent fashion. The frequency-response curves for EFS were displaced to the left by A II and A III, whereas the contractile responses to exogenous acetylcholine remained unchanged. Angiotensin-induced potentiation of the response to EFS was further increased in the presence of physostigmine. These results suggest that A II and A III may prejunctionally potentiate the vagally-mediated contraction of airway smooth muscle.

Acetylcholine↗

PubMed1992

[Airway epithelial beta 3-adrenergic receptor--effect on bioelectric properties and its mechanism of action].

To characterize the "atypical" beta-adrenergic receptor (beta 3-adrenergic receptor) and its action on ion transport across airway mucosa, we measured the bioelectric properties of canine cultured tracheal epithelium under short-circuited conditions in vitro. Submucosal but mucosal addition of BRL37344, a selective beta 3-adrenergic agonist, increased short-circuit current (Isc) in a dose-dependent fashion, the EC50 value being 30 fold higher than that of isoproterenol. This effect on Isc was accompanied by the accumulation of intracellular cyclic AMP, and it was abolished by diphenylamine-2-carboxylate, bumetanide, and Cl-free medium, but not by amiloride. Pretreatment of cell with beta 1- and beta 2-adrenergic antagonists greatly reduced the Isc response to isoproterenol, whereas it had little effect on the BRL37344-induced response. In addition, the increase in Isc produced by BRL37344 was competitively antagonized by cyanopindolol, but pA2 was significantly different from the case of isoproterenol. These results suggest that beta 3-adrenergic receptors exist on airway epithelium, and may stimulate Cl secretion across the airway mucosa via accumulation of intracellular cyclic AMP.

Adrenergic beta-Agonists↗

PubMed1992

[Pharmacological evidence for the existence of beta 3-adrenergic receptors in canine airway smooth muscle].

There is increasing evidence for the existence of a third atypical beta-adrenergic receptor (beta 3-adrenoceptor) in various tissues including adipocytes, cardiac myocytes and intestinal smooth muscle preparations. In the present study, to determine whether beta 3-adrenoceptors also exist in the airway smooth muscle, we studied isolated bronchial segments from dogs under isometric conditions in vitro. Application of beta-adrenoceptor agonists produced a concentration-dependent relaxation of tissues precontracted with 10(-5) M acetylcholine, the order of potency being isoproterenol (1) > or = salbutamol, a beta 2-selective adrenoceptor agonist (0.95) > or = BRL 37344, a beta 3-selective adrenoceptor agonist, (0.83) >> norepinephrine (0.10). Under the condition in which alpha- and beta 1-adrenoceptors had been blocked by phentolamine and ICI 89406, respectively, the relaxant response to salbutamol was competitively antagonized by the beta 2-adrenoceptor antagonist ICI 118551, and the pA2 value was 7.01 +/- 0.25 (mean +/- SE), whereas the response to BRL 37344 was resistant, with of apparent pA2 value of 5.66. However, cyanopindolol, an antagonist atypical beta-adrenoceptors, antagonized BRL 37344-induced relaxation in a competitive fashion with a pA2 of 6.74 +/- 0.11. This pA2 value was lower than that when salbutamol was used as an agonist (p < 0.05). These results indicate that beta 3-adrenoceptors probably exist in canine bronchial smooth muscle, and that stimulation of this type of receptors produces potent bronchodilation. Therefore, a specific agonist for beta 3-adrenoceptors could be valuable in the treatment of asthma.

Acetylcholine↗

PubMed1992

The anti-asthmatic agent KC 404 inhibits sodium absorption by canine tracheal epithelium.

To elucidate the effect of KC 404, an anti-asthmatic agent, on electrolyte transport across airway mucosa, we studied electrical properties of canine tracheal epithelium under isometric conditions in vitro. Addition of KC 404 decreased short-circuit current, transepithelial potential difference and cell conductance, accompanied by the decrease in 22Na flux from submucosa to mucosa. The KC 404-induced decrease in short-circuit current was inhibited by amiloride but not by diphenylamine-2-carboxylate. These results suggest that KC 404 selectively inhibits Na absorption by airway epithelium, thereby leading to the increase in water content in the respiratory lumen.

Absorption↗

PubMed1992

[Effect of saibokuto on mucociliary transport system in the airway--basic and clinical assessments].

We studied the effects of Saibokuto, an antiasthmatic agent, on the airway mucociliary transport system. The addition of Saibokuto to a Rose chamber containing rabbit cultured tracheal epithelium dose-dependently increased ciliary beat frequency (CBF) as assessed by a photoelectric method: the maximal increase from the baseline value was 31.5 +/- 5.2% (p less than 0.001) and the concentration of Saibokuto required to produce a half-maximal effect (EC50) was 10(-4) mg/ml. This effect was not affected by the beta-adrenergic receptor antagonist propranolol or Ca(2+)-free medium, but was inhibited by the cyclooxygenase inhibitor indomethacin. Intracellular cyclic AMP levels were increased from 45.6 +/- 8.2 to 72.1 +/- 12.6 pmole/mg protein by 1.0 mg/ml Saibokuto (p less than 0.05). Thus, Saibokuto enhances ciliary motility probably through the synthesis of cyclooxygenase products and cyclic AMP. Additionally, administration of this drug to patients with chronic bronchitis, asthma and bronchiectasis improved their problems with sputum expectoration and reduced the amount of daily sputum (p less than 0.001). Therefore, Saibokuto may be of value in the treatment of patients with impaired mucociliary transport function in the airway.

Animals↗

PubMed1992

Erythromycin inhibits Cl secretion across canine tracheal epithelial cells.

We studied the effect of the macrolide antibiotic erythromycin on bioelectrical properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. Addition of erythromycin to the submucosal but not to the mucosal side dose-dependently decreased short-circuit current (Isc), the maximal decrease from the baseline value and the concentration required to produce a half-maximal effect (IC50) being 5.6 +/- 1.0 microA.cm-2 (mean +/- SE, p less than 0.001) and 18 microM, respectively. In contrast, other antibiotics including ampicillin, cephazolin and tetracycline were without effect. The erythromycin-induced decrease in Isc was not altered by amiloride, but it was abolished by bumetanide, diphenylamine-2-carboxylate2, and substitution of Cl in the bathing medium with gluconate (p less than 0.001, in each case). The effect of erythromycin on epithelial Isc was attenuated by pretreatment of cells with indomethacin but not with AA-861 a lipoxygenase inhibitor. Incubation of cells with erythromycin inhibited the release of prostaglandins E2 and F2 alpha from tracheal epithelial cells. These results indicate that erythromycin may selectively inhibit Cl secretion across airway epithelium through the inhibition of prostaglandin synthesis and suggest that this action possibly reflects its clinical efficacy in the treatment of airway hypersecretion.

Animals↗

PubMed1991

Vasoactive intestinal peptide stimulates ciliary motility in rabbit tracheal epithelium: modulation by neutral endopeptidase.

We studied the effect of vasoactive intestinal peptide (VIP) on ciliary activity in rabbit cultured tracheal epithelium by a photoelectric method in vitro. Administration of VIP (10(-7) M) elicited an increase in ciliary beat frequency (CBF) from the baseline values of 970 +/- 52 to 1139 +/- 75 beats/min (mean +/- S.E., P less than 0.01). This ciliostimulatory effect was dose-dependent, with the maximal increase and EC50 value being 17.4 +/- 1.0% (P less than 0.05) and 6.10(-11) M, respectively. The VIP-induced increase in CBF was abolished by pretreatment of cells with [4-Cl-D-Phe6, Leu17]-VIP, a VIP receptor antagonist. The neutral endopeptidase inhibitor phosphoramidon (10(-5) M) potentiated the effect of VIP, so that the CBF dose-response curve for VIP was shifted to lower concentrations by 0.5 log U. The administration of VIP increased cyclic AMP levels in epithelial cells, an effect that was also potentiated by phosphoramidon. These results suggest that VIP may interact with its specific receptors and stimulate airway ciliary activity probably through the activation of adenylate cyclase, and that neutral endopeptidase may play a role in modulating this effect of VIP.

Animals↗

PubMed1991

Effect of IgE-stimulated alveolar macrophages on tracheal epithelial bioelectric properties in dogs.

To investigate a possible interaction between pulmonary alveolar macrophages (AMs) and airway epithelial cells in patients with allergic conditions, we studied the effect of AMs on bioelectric properties of canine tracheal epithelium under short-circuited conditions in vitro. Mucosal addition of the supernatants from AMs stimulated with monoclonal antidinitrophenyl (DNP) IgE antibody and DNP-human serum albumin (DNP-HSA) increased short-circuit current (Isc) of cultured epithelium in a dose-dependent manner. The maximal increase from the baseline value and the EC50 were 10.2 +/- 2.0 microA/cm2 (mean +/- SE, p less than 0.01) and 3 x 10(5) AMs/ml, respectively. This effect was accompanied by the release of prostaglandin E2 and F2 alpha from AMs. In contrast, AMs incubated with anti-DNP IgE antibody alone or DNP-HSA alone had no effect. The AM-induced increase in Isc was attenuated by diphenylamine-2-carboxylate and Cl-free medium but not by amiloride. Pretreatment of AMs with indomethacin or piroxicam inhibited the effect of AMs on epithelial Isc. These results suggest that AMs may stimulate Cl secretion across the airway mucosa through an IgE-dependent release of prostaglandins.

Animals↗

PubMed1991

Effects of platelet-activating factor on bioelectric properties of cultured tracheal and bronchial epithelia.

To elucidate the effect of platelet-activating factor (PAF) on ion transport function of airway epithelial cells, we studied bioelectric properties of cultured tracheal and bronchial epithelia from dogs under short-circuit conditions in vitro. Addition of PAF (10(-5) mol/L) to mucosal solution of Ussing chamber increased short-circuit current of tracheal epithelium from 3.3 +/- 0.7 to 8.5 +/- 1.2 microA/cm2 (p less than 0.001). This effect was dose dependent, and there was a corresponding increase in transepithelial potential difference. In contrast, PAF was without effect when it was added to the submucosal side. Electrical properties of bronchial epithelium remained unchanged by PAF. The PAF-induced increase in short-circuit current was not affected by amiloride but abolished by diphenylamine-2-carboxylate, bumetanide, or Cl-free medium. The effects of PAF were not altered by AA-861 or U-60257, but attenuated by indomethacin and piroxicam, and dose-dependently blocked by CV 6209 and WEB 2086. Mucosal, but not submucosal, addition of PAF increased the rate of prostaglandin release from tracheal epithelium. These results suggest that PAF selectively stimulates Cl secretion across tracheal epithelium, probably through activation of its specific receptors and the subsequent production of prostaglandins.

Action Potentials↗

PubMed1991

IgE-dependent activation of alveolar macrophages augments neurally mediated contraction of small airways.

1. We studied the effect of immunologically activated pulmonary alveolar macrophages (PAM) on functions of canine bronchiolar smooth muscle under isometric conditions in vitro. 2. PAM, stimulated with monoclonal anti-dinitrophenyl (DNP) IgE antibody and DNP-human serum albumin (DNP-HSA), augmented the contractile responses of bronchioles to electrical field stimulation, whereas PAM treated with IgE antibody alone had no effect. 3. In contrast, the contractile responses to exogenously administered acetylcholine were not influenced by immunologically activated PAM. 4. The PAM-induced increase in the contractile responses to field stimulation was inhibited by pretreatment of PAM with indomethacin and by addition of the thromboxane A2 (TxA2) receptor antagonist SQ 29548. 5. The release of TxA2 from PAM was increased by anti-DNP IgE and DNP-HSA, an effect that was prevented by indomethacin. 6. These results suggest that PAM may play a role in the development of antigen-induced hyperreactivity of small airways through an IgE-dependent release of TxA2 which potentiates prejunctionally the parasympathetic component of bronchiolar smooth muscle tone.

Acetylcholine↗

PubMed1991

Stimulation of airway ciliary motility by immunologically activated canine pulmonary macrophages: role of leukotrienes.

To elucidate a possible interaction between alveolar macrophages and airway epithelial cells in allergic conditions, we studied the effect of immunologically stimulated macrophages on ciliary beat frequency (CBF) of cultured canine tracheal epithelium by a photoelectric method. Administration of supernatants from macrophages incubated with anti-dinitrophenyl (DNP) IgE antibody and anti-dinitrophenyl-human serum albumin dose-dependently increased ciliary beat frequency, the maximal increase from the baseline being 30.4 +/- 5.0% (mean +/- SE, P less than 0.01), an effect that was accompanied by the release of leukotriene (LT) C4 and leukotriene D4. This ciliostimulation was not affected by pretreatment of macrophages with indomethacin but was inhibited by that with nordihydroguaiaretic acid. Addition of FPL 55712 abolished the response of ciliary beat frequency to the stimulated macrophages, and exogenously administered leukotriene C4 and leukotriene D4 dose-dependently increased ciliary beat frequency. These results suggest that macrophages increase respiratory ciliary motility through the IgE-mediated release of leukotrienes and may modulate mucociliary transport function in the airway.

Animals↗