Nitric oxide and airway reactivity.
BACKGROUND
Nitric oxide is a neurotransmitter of the inhibitory nonadrenergic noncholinergic mediation in the respiratory system. Its participation in the regulation of airways functions is determined by its level in the organism.


OBJECTIVE
We examined participation of nitric oxide in the changes of the airway reactivity evoked by toluene exposure as the source of the free radicals. The changes of nitric oxide level in the organism were evoked by administration of its indirect donor isosorbide dinitrate. Thiol groups were provided by administration of antioxidative mucolytic N-acetylcysteine.


METHODS
Used drugs--isosorbide dinitrate (5 mg/kg b.w.) and N-acetylcysteine (300 mg/kg b.w.) were administered intraperitoneally or by inhalation 30 minutes before each exposure to the toluene vapours. The control group was not treated with drugs. After toluene exposure (2 hours in each of 3 consecutive days) tracheal and lung strips smooth muscle reactivity to histamine was observed under in "in vitro" conditions.


RESULTS
The administration of isosorbide dinitrate decreased especially the lung strip smooth muscle reactivity to histamine. We revealed more expressive effect of the pretreatment with intraperitoneally administered isosorbide dinitrate in the comparison with inhalation. Simultaneous pretreatment with N-acetylcysteine intensified beneficial effect of isosorbide dinitrate probably by increasing of the intracellullary level of thiols.


CONCLUSIONS
In our experimental conditions possible participation of nitric oxide in changes of airways smooth muscle reactivity after exposure to the toluene follows from results, as well as the importance of thiol groups for the activity of its indirect donors. (Fig. 6, Tab. 3, Ref. 35.)
Strapkova
A
A
Dept of Pharmacology, Jessenius Faculty of Medicine, Comenius University, Sklabinska 26, SK-037 53 Martin, Slovakia.
Nosalova
G
G
D000111:Acetylcysteine / Q000008:administration & dosage / Q000494:pharmacology; D000280:Administration, Inhalation; D000818:Animals; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007548:Isosorbide Dinitrate / Q000008:administration & dosage / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D014050:Toluene / Q000494:pharmacology*; D014132:Trachea / Q000187:drug effects* / Q000502:physiology
D018377:Neurotransmitter Agents; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D014050:Toluene; D006632:Histamine; D007548:Isosorbide Dinitrate; D000111:Acetylcysteine