1. Hypertension-prone Dahl S rats on either low or high NaCl diets have less than half the concentration of prostaglandin E2 (PGE2) in quick-frozen renal papillae compared with that of hypertension-resistant Dahl R rats.
2. A 4% high NaCl diet doubles the concentration of PGE2 in the renal papillae compared with the effect of a moderately low (0.3%) NaCl diet.
3. A diet with 16% linoleic acid triples the PGE2 concentration in S papillae and increases it 2.5 times in R papillae, compared with a diet with 1.5% linoleic acid.
4. The 16% linoleic acid diet also delays the onset of NaCl-induced hypertension and prevents about half of the ultimate rise in blood pressure.
5. The low PGE2 concentration in the renal papillae of S rats could contribute to a tendency toward sodium retention and thereby encourage NaCl-induced hypertension.
6. Thiazides greatly increase sodium and water excretion in isolated kidneys from pre-hypertensive S rats perfused with blood at a normotensive arterial inflow pressure. This effect would allow brisk natriuresis without the need for hypertensive arterial pressures and could thereby reduce blood pressure in NaCl-related hypertension.