Effect of arachidonic acid on the basal release of prostaglandins E2 and I2 by rat arteries during the development of hypertension.

The ability of aortic strips from 5, 10 and 20 week old spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) and Wistar (W) rats to release prostaglandin (PG) E2 and I2 was examined both in the presence and absence of arachidonic acid (AA). Strips from SH rats older than 5 weeks generally synthesized more PGE2 than those from age-matched control rats. Strips from age-matched SH and W rats synthesized the same amounts of PGI2 and both released more than those from age-matched WKY rats. Although the actual quantities of PGE2 or PGI2 released varied between strips from W and WKY rats, the PGI2/PGE2 ratio was always the same and doubled with the addition of AA. In contrast, the PGI2/PGE2 ratio for SH rats did not increase with the addition of AA and was only one-half that of W or WKY rats. These data demonstrate that arteries from normotensive rats preferentially synthesize PGI2 whereas those from SH rats metabolize AA to proportionally more PGE2.