1. Potassium citrate did not significantly increase plasma flow to the renal papilla in normotensive Dahl R rats on either low or high NaCl diets. Similarly, potassium citrate did not significantly increase papillary plasma flow in mildly hypertensive Dahl S rats on low NaCl diets. Thus potassium citrate feeding did not ordinarily alter papillary plasma flow.
2. When S rats were fed on a high (4%) NaCl diet for 24 weeks, they became severely hypertensive and developed nephrosclerosis with nephron loss. This accounted for the significant reduction in papillary plasma flow in S rats on 4% high NaCl diet with no potassium supplementation.
3. When S rats on high NaCl diet were given a supplement of KCl, they still developed severe hypertension and almost the same fall in papillary plasma flow, suggesting a similar degree of nephron loss from nephrosclerosis.
4. However, when S rats on high NaCl diet were given a supplement of potassium citrate, they still developed the same severe hypertension but, in contrast, they did not have a decrease in papillary plasma flow. This actually increased to 7% higher than in comparable S rats eating the low NaCl diet. Moreover, S rats receiving potassium citrate supplements in their high NaCl diet had a papillary plasma flow which was 34% higher than that of S rats receiving no potassium supplement in the high NaCl diet (P < 0.005) and was 19% higher than that of S rats receiving KCl supplements in the high NaCl diet (P < 0.04). This occurred even though the rats receiving potassium citrate were severely hypertensive.
5. Thus potassium citrate feeding protected against nephron loss from nephrosclerosis during severe NaCl-induced hypertension, whereas KCl feeding did not provide such protection.