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Antagonism of some smooth muscle actions of prostaglandins by polyphloretin phosphate
Author(s) -
EAKINS K. E.,
KARIM S. M. M.,
MILLER J. D.
Publication year - 1970
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.1476-5381.1970.tb10363.x
Subject(s) - antagonism , muscle contraction , phosphate , chemistry , smooth muscle , endocrinology , pharmacology , medicine , biology , biochemistry , receptor
1 The antagonism of the smooth muscle stimulating actions of PGF 2α and PGE 2 by polyphloretin phosphate (PPP) was studied on several isolated smooth muscle preparations and on the blood pressure of the anaesthetized rabbit. 2 PPP (2·5–20 μg/ml) reversibly inhibited contractions of the jird colon produced by PGE 2 or PGF 2α ; PGF 2α was more readily antagonized than PGE 2 . 3 PPP (2·5–30 μg/ml) reversibly antagonized contractions produced by PGE 2 and PGF 2α on the isolated rabbit jejunum and uterus. In these preparations PPP antagonized PGE 2 as readily as PGF 2α . 4 It is concluded that PPP is a selective antagonist to the prostaglandins on these tissues, for contractions produced by other agonists, such as acetylcholine, angiotensin, 5‐hydroxytryptamine and bradykinin were not reduced by concentrations of PPP which markedly antagonized responses to the prostaglandins. 5 Intravenous injections of PPP (25–200 mg/kg) resulted in a variable antagonism to the fall in blood pressure produced by intravenous injections of PGF 2α in the anaesthetized rabbit; vasodepressor responses produced by PGE 2 and acetylcholine were not antagonized. 6 The mechanism of this antagonism by PPP is not clear and must await further investigation.