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màj 23/07/98 |
Report
by S. Matecki on the following session :
Samedi 14 Février 1998
|
Présentateurs
|
Modérateurs
|
Experts
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8h30-9h30
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Muscle lisse
Smooth
muscle
|
M. Molimard
(Paris)
J.M.
Tunon de Lara (Bordeaux)
Discussion
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15'
15' 30'
|
R.
Marthan (Bordeaux)
J. Mercier (Montpellier)
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F.P.
Nijkamp (Utrecht, NL)
K. Rabe (Grossandorf, D)
|
M.
Molimard spoke about the influence of
lipopolysaccharide (LPS) and Interleukine 1-ß (IL1-ß)
on human isolated bronchi responsiveness to bradykinin,
substance-P and neurokinine A.
LPS and IL1-ß involved in the inflammatory response,
enhance in vitro the contraction of human isolated
bronchus response to bradykinin. This effect is time
dependent, and it is abolished by indomethacin. This
inhibition exist also with thromboxane A2 antagonist and
bradykinin B2 receptor antagonist. It seemed that
responsiveness to bradykinin was mediated by thromboxane
receptor stimulation. But the cyclooxygenase 2 inhibitor
failed to demonstrate an inhibitory effect of IL1-ß on
human isolated bronchi responsiveness to bradikinin. The
inhibition of indomethacin on the relaxation of human
control bronchi in response to bradykinin in the presence
of thromboxane receptor antagonist is not modified by
IL1-ß pre-treatment. Similar results were found on
airway smooth muscle cell responsiveness to substance P.
Substance P induced contraction was also mediated by
thromboxane receptor stimulation, but on the oppposite,
cyclooxygenase 2 inhibitor inhibit the IL1-ß induced
potentiation of the substance P effect. Same experiments
were performed with neurokinin A, but with slightly
effect of IL1-ß on the smooth muscle cell
responsiveness. In conclusion, it seems that IL1-ß
potentiate the effect of bradykinin or tachykinin
receptor agonist on the human isolated bronchi. The
mechanism might involve regulation of thromboxane
synthesis and cyclooxygenase synthesis.
|
Discussion
Mr Nijkamp insit on the importance of the bradykinin's role on
the activation of airway smooth muscle cell. He said that
induction of a treatment may enhance bronchi responsiveness to
bradykinin and so it is possible to induce relaxation of smooth
cell.
Mr Rabe ask about the range of variation responsiveness to
bradykinin with IL1-ß and substance P.
Mr Olivieri wanted to know if influence of LPS and IL1-ß on
smooth muscle cell have been measured only at 1 and 6 hours of
incubation.
Mr Molimard answered that he measured the effect of LPS and
IL1-ß at every hours of incubation but in his presentation he
only presented the main results.
J.M.
Tunon de Lara spoke
about the IgE passive sensitization of human isolated bronchi and
lung mast cells.
Passive sensitization of human isolated airways with serum
from allergic asthmatic patients provides a good opportunity to
study the role of IgE in bronchial reactivity. This serum with
high concentration of IgE induce hyperresponsiveness of human
isolated smooth cell in the airways. This passive sensitization
is mainly related to mast cells bearing IgE molecule in
differents smooth muscle layers. Derived products of the mast
cells such as tryptase could enhance the contractile response of
human isolated airways to non specific agonists such as
histamine, KCl and tachynin. This effect is inhibited by the
tryptase inhibitor benzamidine. Mast cell-derived products could
contribute to sentitisation-induced hyperresponsiveness.
. 
Enfumosa Congrès Conçue et réalisée par: Michel Godard (at) Top
Date de création: 12 Février 1998 -Dernière mise à jour: 23/07/98
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