In this paper we present the flow research of the development of receptor bronchial system in the first month of extra-uterine life up to the sixth month of development, performed by tracking the reactions of isolated tracheal rings in acetylcholine (Ach), propranolol (P), histamine (Hist), and prostaglandin (PG F2-alfa) in concentrations of: 10-4, 10-3, 10-2 and 10-1 mol/dm3; in piglets of ages: 1 month, 2 months, 4 months and 6 months. Results shows that Ach causes reaction of smooth muscles from the first month of extra-uterine life (p0.1), while histamine and PGF2- alpha do not cause constriction (histamine up to 4 months of age, PGF2-alfa up to 6 months of extra-uterine life). This shows that cholinergic and adrenergic system in piglet airways is developed during intrauterine life and reaction can be registered in the first month of extra-uterine life, while other receptor systems are developed in later periods of extra-uterine life. This suggests that lack of reaction of tracheal smooth musculature (TSM) comes as a result of sufficient non-maturity of mast cells from which chemical mediators, with local functioning, are released.
Key words: piglet trachea, AC h, propranolol, histamine, PGF2-alfa
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