AJP - Heart and Circulatory Physiology, Vol 244, Issue 2 228-H233, Copyright © 1983 by American Physiological Society
Dietary linoleic acid deprivation: effects on blood pressure and PGI2 synthesis
R. Dusing, R. Scherhag, K. Glanzer, U. Budde and H. J. Kramer
The possible role of arachidonic acid metabolites in the regulation of
arterial blood pressure was investigated in rats receiving 0, 5, or 9
energy (en) % linoleic acid in their diet (groups 1-3) over 6 wk. In group
1 animals, systolic arterial blood pressure significantly increased from
100.5 +/- 2.0 to 110.6 +/- 3.1 mmHg (P less than 0.01) after 6 wk of
dietary linoleic acid deprivation, whereas no effect on blood pressure was
observed in group 2 and 3 animals receiving dietary linoleic acid
supplements. Generation of prostacyclin (PGI2)-like activity by isolated
aorta from rats fed the different diets was determined using a
platelet-aggregation bioassay following incubation of aortic tissue for 12,
15, and 30 min, respectively. In isolated aorta from rats fed the 5 en%
linoleic acid, production of PGI2 was 55.9 +/- 1.2, 70.5 +/- 2.6, and 90.9
+/- 3.6 pmol/mg over the three incubation periods. In group 1 animals, a
significant suppression of PGI2 generation to 35.4 +/- 1.5, 41.1 +/- 1.7,
and 55.0 +/- 1.2 pmol/mg (P less than 0.005) was observed, whereas PGI2
production was unaltered in aortic tissue from group 3 animals. In
contrast, plasma concentrations of circulating thromboxane B2 were highest
in group 1 animals (2.15 +/- 0.38 pmol/ml) and measured 1.28 +/- 0.17 and
0.83 +/- 0.10 pmol/ml in group 2 and 3 animals, respectively. Our results
demonstrate that dietary deprivation of the arachidonic acid precursor
linoleic acid increases arterial blood pressure that is associated with a
suppression of vascular PGI2 synthesis and, most likely, a secondary rise
in circulating thromboxane concentrations.
