Dietary sodium restriction and blood pressure response to sympathetic blockade in young versus adolescent spontaneously hypertensive rats.
The effects of dietary sodium restriction on the maintenance of blood pressure (BP) by sympathetic tone were evaluated in young versus more mature spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Sympathetic activity was assessed by BP responses to alpha 1-receptor blockade (prazosin), central inhibition of sympathetic outflow (clonidine), and by ganglionic blockade (hexamethonium). On regular sodium intake, SHR showed elevated BP and increased BP responses to sympathetic blockade at both 10 and 16 weeks of age. Sodium restriction to 9 or 17 mumols Na+/g food prevented or blunted development of hypertension in SHR when started at 4 weeks of age but did not affect BP when started at 10 weeks of age. Sodium restriction initiated in young SHR also prevented development of increased BP responses to sympathetic blockade. However, sodium restriction in more mature SHR did not decrease the increased BP responses to sympathetic blockade. We conclude that prevention of development of sympathetic hyperactivity in young SHR represents a major mechanism in the antihypertensive effect of sodium restriction in young SHR.
Leenen
F H
FH
Hypertension Unit, Toronto Western Hospital, Ont., Canada.
Klement
G
G
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology; D004039:Diet, Sodium-Restricted; D006339:Heart Rate / Q000187:drug effects; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012964:Sodium / Q000652:urine; D013565:Sympatholytics / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D006584:Hexamethonium Compounds; D013565:Sympatholytics; D012964:Sodium; D003000:Clonidine; D011224:Prazosin