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Sodium balance as a determinant of prostacyclin production by isolated rat aorta
Author(s) -
DÜSING R.,
LANDSBERG G.,
PIETSCH R.,
SCHERHAG R.,
SÖNTGERATH C.,
KRAMER H. J.
Publication year - 1987
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1987.tb02189.x
Subject(s) - prostacyclin , aorta , incubation , sodium , endocrinology , medicine , saline , chemistry , zoology , distilled water , biochemistry , biology , chromatography , organic chemistry
. The present study investigates whether the synthesis of prostacyclin (PGI 2 ) in isolated rat aorta is dependent on the state of sodium balance of the animals. Three groups of ten rats each were included into the study. Two of them were fed a diet low in NaCl for 10 days with group I receiving 0·9% saline and group II distilled water as drinking fluid. Group III received a regular rat chow containing approximately 0·8 mmol day ‐1 of sodium, also for 10 days. At the end of the dietary protocol, systolic arterial blood pressure was significantly higher in group I (109·9 ± 2·4 mmHg) as compared to group II (101·0 ± 2·4 mm Hg; P < 0·05) and group III animals (102·2±1·6 mm Hg; P <0·05). Generation of PGI 2 ‐like activity was determined in portions of the animals' isolated aorta using a platelet aggregation bioassay following incubation in 0·05 m Tris buffer (pH 9·3) for 12, 15, and 30 min, respectively. During these incubation times, generation of PGI 2 ‐like activity averaged 48·6 ± 3·5, 57·8 ± 4·3 and 68·3 ± 3·2 pmol mg ‐1 in group III animals, which had received the regular rat chow, with similar values in the low salt group II (50·2 ± 2·5, 57·7 ± 2·7 and 72·9 ±3·7 pmol mg ‐1 ). Aortic generation of PGI 2 ‐like material was significantly suppressed in the high salt group I (37·5 ± 2·8, 46·2 ± 3·2 and 61·3 ± 4·0 pmol mg ‐1 ; P <0·01). When added directly into the incubation buffer, norepinephrine and the α‐receptor agonist phenylephrine (100 n m ) induced a significant stimulation of the generation of PGI 2 ‐like activity while the β ‐receptor agonist isoproterenol had no effect. Our results show that the significantly increased arterial blood pressure during chronic NaCl loading is accompanied by suppressed vascular synthesis of PGI 2 . This may be mediated, at least in part, by changes in α‐adrenergic activity.