[New insight into nitric oxide involvement in regulation of airways smooth muscle tone].
All three isoforms of NO synthases (NOS) were localised in the lung and are involved in regulation of airways and pulmonary vessels smooth muscle tone and inflammatory response. The participation of nitric oxide in the regulation of airways smooth muscle has not been understood yet.


METHODS
We studied age-related variation of NO secretion on three lots of bronchi rats: young (4-6 weeks), adults (2-3 months), old (12-14 months). The implied of NO synthesis on airways smooth muscle tone was indirectly investigated by blocking NOS with N(omega)-nitro-L-arginine methyl ester (L-NAME).


RESULTS
Pre-treatment of isolated bronchi rings with 0.1 mM L-NAME amplified both tonic contractions induced by cumulative doses of acetylcholine (0.1 nM - 1mM) and various doses of angiotensin II (10 nM - 10 eM). L-NAME actions were lower on old than young rats: at least two times for ACh and three times for Ang II. These results suggest that NO actions decrease with age. Decrease of NO activity on airways was described in pathological states like asthma.


CONCLUSIONS
Decrease of NO activity would generate increase of airway smooth muscle tone and would explain partially aging changes on airway reactivity.
Dumitriu
Irina Luciana
IL
Facultatea de Medicină, Departmentul de Fiziologie, Universitatea de Medicină i Farmacie "Gr.T. Popa" Iaşi.
Petrescu
B C
BC
Gurzu
Mihaela Beatrice
MB
Gurzu
B
B
Slătineanu
Simona Mihaela
SM
D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D001993:Bronchodilator Agents / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D001993:Bronchodilator Agents; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester