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Prostaglandins involved in contractions by angiotensin II and bradykinin of isolated dog sphincter pupillae
Author(s) -
Lu Wei,
Okamura Tomio,
Bian Ka,
Inatomi Akihiro,
Toda Noboru
Publication year - 1988
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.1476-5381.1988.tb11675.x
Subject(s) - bradykinin , endocrinology , medicine , chemistry , saralasin , prostaglandin , angiotensin ii , arachidonic acid , thromboxane a2 , antagonist , receptor , biochemistry , enzyme
1 The dog isolated sphincter pupillae contracted in response to acetylcholine, angiotensin II (AII), bradykinin, prostaglandins F 2α , D 2 , E 2 and I 2 , and thionate thromboxane A 2 (sTXA 2 ) in a concentration‐dependent manner. 2 AII‐induced contractions were suppressed by treatment with saralasin, indomethacin, aspirin and diphloretin phosphate (DPP), a prostaglandin receptor antagonist. Contractions induced by bradykinin were also attenuated by indomethacin, aspirin and DPP. The amount of prostaglandin F 2α (PGF 2α ) in the bathing media was increased approximately 41% following stimulation of the preparations by bradykinin. 3 The potency of contractile responses was in the order of PGF 2α > PGD 2 = sTXA 2 > PGE 2 > arachidonic acid > PGI 2 . Contractions induced by PGF 2α were not significantly affected by treatment with indomethacin and ONO3708, an antagonist of the vasoconstrictor effect of prostaglandins, but appreciably attenuated by DPP. Arachidonic acid‐induced contractions were inhibited by indomethacin. 4 Contractions of dog iris sphincter muscle in response to AII and bradykinin may be mediated via substances synthesized by cyclo‐oxygenase from arachidonic acid. The distribution and nature of the prostaglandin receptors appear to differ markedly in iris sphincter and vascular smooth muscles.