Premium
THE MECHANISM OF THE RELAXANT EFFECT OF 2‐2′‐PYRIDYLISATOGEN ON THE ISOLATED TAENIA OF THE GUINEA‐PIG CAECUM
Author(s) -
SPEDDING M.,
WEETMAN D.F.
Publication year - 1978
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1978.tb17279.x
Subject(s) - caecum , guinea pig , taenia , pharmacology , chemistry , anatomy , biology , medicine , endocrinology , zoology , helminths
1 2‐2′‐Pyridylisatogen tosylate (PIT) slowly relaxed taenia caeci preparations of the guinea‐pig in a concentration‐dependent manner (threshold 2.5 μ m ). The relaxant effect did not show tachyphylaxis. 2 The relaxation was not affected by tetrodotoxin (0.3 μ m ), guanethidine (17 μ m ) nor by a combination of phentolamine (36 μ m ) and propranolol (4 μ m ) 3 In taenia caeci preparations suspended in K + ‐depolarizing, Ca 2+ ‐free Ringer, addition of Ca 2+ (0.1 to 30 m m ) resulted in a slow contraction. PIT (50 μ m ) and papaverine (15 μ m ) antagonized these contractions, whereas indomethacin (28 μ m ) was ineffective. 4 Although PIT (50 μ m for 30 min) caused a relaxation of the taenia, and, when the tone of the preparations was restored with carbachol, antagonized adenosine 5′‐triphosphate (ATP)‐induced relaxations, relaxation of the taenia with papaverine (30 μ m for 5 min) did not antagonize ATP‐induced relaxations. It is concluded that the relaxant and ATP‐receptor blocking actions of PIT are independent properties of the compound.