Cerebral and renal alpha-adrenoceptors in Sabra hypertensive (SBH) and normotensive (SBN) rats: effects of high-sodium diet.
The aim of the present study was to investigate the effect of high (8%) versus normal (0.2%) sodium diet on cerebral and renal alpha-adrenoceptors of Sabra hypertensive (SBH) and normotensive (SBN) rats. Cerebral alpha 2-adrenoceptor densities were higher in SBN than in SBH rats. In contrast, renal alpha 2-adrenoceptor density was higher in SBH than in SBN rats. No difference in alpha 1-adrenoceptor densities was observed between the two strains. After 2 and 5 weeks of high-sodium diet, alpha 2-adrenoceptor densities were increased in renal cortex of SBH and SBN rats. In contrast, cerebral alpha 2-adrenoceptor densities were markedly decreased in SBN but not in SBH rats. alpha 1-Adrenoceptor densities were unchanged by high salt intake. Blood pressure increased only after 5 weeks of high-sodium diet, markedly in SBH and to a lesser extent in SBN rats. The variation in alpha 2-adrenoceptor densities thus preceded the blood pressure elevation. The dietary sodium-induced increase in renal alpha 2-adrenoceptor densities observed both in SBH and SBN rats does not appear to be a genetic marker of hypertension. In contrast, the marked decrease in cerebral alpha 2-adrenoceptors in SBN rats may represent an adaptative change in sympathetic activity responsible for the resistance to the development of salt-induced hypertension.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D006973:Hypertension / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008566:Membranes / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D012964:Sodium / Q000008:administration & dosage*; D013997:Time Factors; D015016:Yohimbine / Q000378:metabolism
D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D012964:Sodium; D011224:Prazosin