Dietary sodium modification and experimental radiation nephropathy.
OBJECTIVE
To determine whether suppression of the renin-angiotensin system (RAS) with high dietary sodium (salt) has the same beneficial effect on radiation nephropathy as suppression of the RAS with angiotensin-converting-enzyme (ACE) inhibitors or angiotensin II (AII) receptor antagonists.


METHODS
Normal and irradiated rats were placed on high- or low-salt diets and assessed for effects on blood pressure, on AII levels and on the development of radiation nephropathy.


RESULTS
In unirradiated animals, a high-salt diet suppressed AII and caused hypertension, while a low-salt diet produced no detectable effects. Use of a high-salt diet 3-9 weeks after irradiation exacerbated radiation-induced hypertension but attenuated the development of radiation nephropathy. Continuous use of a high-salt diet slowed the progression of radiation nephropathy, but eventually exacerbated radiation-induced hypertension and accelerated renal failure. Use of a high-salt diet in animals with established radiation nephropathy was deleterious. A low-salt diet had no effect on the development of radiation nephropathy.


CONCLUSIONS
These studies provide further support for the hypothesis that the beneficial effect of AII receptor antagonists, ACE inhibitors and high dietary sodium in the prophylaxis of radiation nephropathy is due to their suppression of the RAS, not to their anti-hypertensive effects.
Moulder
J E
JE
Department of Radiation Oncology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. jmoulder@mcw.edu
Fish
B L
BL
Cohen
E P
EP
D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D016026:Bone Marrow Transplantation; D004039:Diet, Sodium-Restricted; D004305:Dose-Response Relationship, Drug; D007668:Kidney / Q000293:injuries* / Q000528:radiation effects*; D008297:Male; D051381:Rats; D012084:Renin-Angiotensin System; D012965:Sodium Chloride / Q000494:pharmacology*; D013997:Time Factors
D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D012965:Sodium Chloride