Dietary sodium restriction, blood pressure and sympathetic activity in spontaneously hypertensive rats.
Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were started at birth on sodium diets ranging from severely deficient (9 mumol) to a regular intake (101 mumol Na+/g food). Blood pressure and sympathetic activity were assessed at 6 and 16 weeks of age. At either age, SHR on 9 mumol Na+ failed to develop hypertension. Spontaneously hypertensive rats on 17 mumol Na+ exhibited significant blunting of the hypertension; SHR on 26 mumol showed a small amelioration. At 6 weeks, basal plasma noradrenaline was similar in SHR and WKY on 9 and 101 mumol Na+, whereas plasma adrenaline was increased in SHR at the lowest sodium level. At 16 weeks, both catecholamines were significantly increased in SHR on the 9 and 17 mumol sodium diet versus SHR on the control diet. Blood pressure responsiveness to noradrenaline was significantly decreased on 9 mumol Na+, but to a similar extent in both strains. In contrast, the blood pressure lowering effect of ganglionic blockade was markedly blunted in SHR on 9 mumol Na+ and to a lesser extent on 17 mumol Na+ (both for percentage and absolute decrease) and 26 mumol Na+ (only for absolute fall); however, this did not occur in WKY over the diet-range used. We conclude that a sodium-deficient diet from birth prevents/blunts the development of hypertension in SHR, at least partly by decreasing the pressor effect of the sympathetic nervous system.
D000818:Animals; D001794:Blood Pressure; D001835:Body Weight; D004039:Diet, Sodium-Restricted; D004837:Epinephrine / Q000097:blood; D005728:Ganglia, Sympathetic / Q000187:drug effects; D006339:Heart Rate; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006973:Hypertension / Q000097:blood / Q000178:diet therapy* / Q000503:physiopathology; D009407:Nerve Block; D009638:Norepinephrine / Q000097:blood; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D006584:Hexamethonium Compounds; D018738:Hexamethonium; D009638:Norepinephrine; D004837:Epinephrine