Effects of low and high Na diets on cardiovascular dynamics in normotensive and hypertensive rats: neuroeffector characteristics of the resistance vessels.
The aim of the study reported was to explore differences in neuro-effector characteristics of the resistance vessels from normotensive and hypertensive rats (WKY and SHR), which from five to twelve weeks of age had been exposed to either low-sodium (0.5 mM/100 g food), control-sodium (5 mM/100 g) or high-sodium (50 mM/100 g) diet. Isolated small mesenteric arteries (diameter 150-200 microM) were mounted in a two-vessel Mulvany-Halpern myograph. Noradrenaline sensitivity was similar in all arteries. Frequency-response curves of SHR arteries were steeper than in WKY. In both strains low-sodium curves were displaced to higher frequencies with little difference between control and high-sodium curves. Inhibition of the Na-K-ATPase with ouabain enhanced neurogenic responses more than noradrenaline responses, but to similar extents in all sodium groups. The results suggest that chronic low-sodium diet substantially reduces the total adrenergic transmitter release per impulse.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002200:Capillary Resistance / Q000187:drug effects*; D004558:Electric Stimulation / Q000379:methods; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012964:Sodium / Q000008:administration & dosage*; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects*
D012964:Sodium; D009638:Norepinephrine