The lack of compound 48/80-induced contraction in isolated trachea of mast cell-deficient Ws/Ws rats in vitro: the role of connective tissue mast cells.
In the rat trachea, two types of mast cells have been identified, connective tissue mast cells and mucosal mast cells. Their different characteristics may account for their different biological functions. The role of connective tissue mast cells in tracheal contraction as one feature of the immediate reaction of asthma was studied in vitro in isolated trachea, using tissue derived from mast cell-deficient (Ws/Ws) rats, heterozygous (Ws/+) rats and control (+/+) rats, and compound 48/80 as a potent inducer of mast cell degranulation. The contractile response of tracheas from the three types of rats was also studied upon exposure to the following spasmogens: histamine, 5-hydroxytryptamine (5-HT), and carbachol. Histamine content in tissues reflected the differing mast cell numbers in strips from the three rat types. It was found that carbachol and 5-HT elicited tracheal contraction in a similar manner in strips from the three types of rats. Histamine had no contractile effect. Compound 48/80, at a dose of 25 microg/ml, elicited contraction in tracheas from both control (+/+) and heterozygous (Ws/+), but not in trachea from Ws/Ws rats. Compound 48/80-induced contractions in tracheas from +/+ rats were inhibited by 0.1 microM ketanserin and 0.1 microM nedocromil, but not by 0.1 microM mepyramine. Enzyme histochemistry confirmed that the degranulation occurred in connective tissue mast cells, but not in mucosal mast cells. We concluded that connective tissue mast cells play an important role in rat tracheal contraction via 5-HT release induced by compound 48/80. In addition, the specific mast cell-deficient (Ws/Ws) rats provide a good tool for studying the roles of mast cells in airway system.
Ikawati
Z
Z
Department of Pharmacology, Ehime University School of Medicine, Shigenobu-cho, Ehime 791-0295, Onsen-gun, Japan.
Hayashi
M
M
Nose
M
M
Maeyama
K
K
D000818:Animals; D018927:Anti-Asthmatic Agents / Q000494:pharmacology; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology; D003238:Connective Tissue / Q000502:physiology*; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006651:Histocytochemistry; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D008407:Mast Cells / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects*; D017835:Nedocromil / Q000494:pharmacology; D010277:Parasympathomimetics / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects*; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology*
D018927:Anti-Asthmatic Agents; D006634:Histamine H1 Antagonists; D010277:Parasympathomimetics; D012702:Serotonin Antagonists; D017835:Nedocromil; D012701:Serotonin; D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine; D002217:Carbachol; D007650:Ketanserin; D011738:Pyrilamine