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Rabbit brain contains an endogenous inhibitor of endothelium‐dependent relaxation
Author(s) -
Moore P.K.,
AlSwayeh O.A.,
Evans R.
Publication year - 1990
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.1476-5381.1990.tb14172.x
Subject(s) - phenylephrine , sodium nitroprusside , vasodilation , endothelium , acetylcholine , endothelium derived relaxing factor , nitric oxide , lagomorpha , chemistry , arginine , endocrinology , medicine , pharmacology , biochemistry , biology , amino acid , blood pressure
1 Supernatants prepared from the rabbit brain, lung and liver caused an endothelium‐dependent and volume‐related contraction of the phenylephrine‐pretreated rabbit aorta and inhibited relaxation due to acetylcholine (ACh). 2 Perfusion in situ of the rabbit lung or liver with Krebs solution substantially reduced or removed the endothelium‐dependent inhibitor. Spectrophotometric analysis revealed the presence of substantial amounts of haemoglobin (1.8–2.1 μ m ) in these organ supernatants. 3 Supernatants prepared from the Krebs‐perfused rabbit brain retained the ability to contract the phenylephrine‐pretreated rabbit aorta and to inhibit relaxation due to ACh and substance P (SP). Rabbit brain supernatant did not reduce the vasodilator effect of sodum nitroprusside (NP) or nitric oxide (NO). 4 Rabbit brain supernatant contained low (< 0.35 μ m ) concentrations of haemoglobin. 5 The inhibitory effect of rabbit brain supernatant was reversed by l ‐arginine (500 μ m ) but not d ‐arginine (500 μ m ). 6 The inhibitor of endothelium‐dependent vasodilatation present in rabbit brain was not removed by dialysis (24 h, 4°C) but was partially precipitated by ammonium sulphate (30% w/v). 7 Rabbit brain contains an endogenous inhibitor of vascular NO biosynthesis. The identity of this inhibitor is not known although it seems likely to be a large peptide or protein.