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The source of ca 2+ for the spasmolytic actions of longicaudatine, a bisindole alkaloid isolated from Strychnos trinervis (Vell.) Mart. (Loganiaceae)
Author(s) -
de Medeiros C. L. C.,
Thomas G.,
Mukherjee R.
Publication year - 1991
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.2650050107
Subject(s) - verapamil , procaine , alkaloid , histamine , ileum , depolarization , intracellular , bradykinin , carbachol , pharmacology , sodium nitroprusside , biology , brucine , antagonist , calcium , receptor , chemistry , endocrinology , medicine , stereochemistry , biochemistry , strychnine , nitric oxide
Longicaudatine, a tertiary bisindole alkaloid isolated from the root bark of Strychnos trinervis (Vell.) Mart. (Loganiaceae), antagonized in a noncompetitive manner, carbachol and histamine induced contractions of the guinea‐pig ileum and bradykinin responses in the rat uterus. The respective p D 2 ' values (mean ± SE) were 4.61 ± 0.21, 4.98 ± 0.04 and 4.49 ± 0.01. Longicaudatine, unlike verapamil, had no effect on voltage dependent Ca 2+ channels, as it failed to inhibit KCI or CaCl 2 induced contractions of guinea‐pig ileum and depolarized rat uterus respectively. When compared with sodium nitroprusside, an antagonist of receptor operated Ca 2+ channels, longicaudatine produced a slower and weaker inhibition of noradrenaline induced sustained contractions of rabbit aortic strips. However, in the aorta, the alkaloid antagonized the intracellular calcium dependent transient contractions of noradrenaline and longicaudatine (IC 50 , 5.01 × 10 −7 M) was approximately 133 times more potent that procaine (IC 50 , 6.68 × 10 −5 M), a known inhibitor of the release of Ca 2+ from intracellular stores. Longicaudatine may exert nonspecific spasmolytic effects by acting on intracellular Ca 2+ stores, rather than on depolarization dependent or receptor operated Ca 2+ channels.