Increased adrenal catecholamines in salt-sensitive genetically hypertensive Dahl rats

Abstract

Catecholamine levels and activity of catecholamine-forming enzymes have been quantitated in adrenal glands of Dahl sodium-resistant (R) and sodium-sensitive (S), genetically hypertensive rats maintained on low- or high-salt diets. A high-salt diet results in markedly different changes in the catecholamine metabolism in R and S rats. In R rats, a high-salt diet reduces the activities of tyrosine 3-hydroxylase (TH;-5%) and dopamine beta-hydroxylase (DBH; -18%) as well as the levels of all catecholamines (dopamine -28%, norepinephrine -11%, and epinephrine -28%). In contrast, S rats fed a high-salt diet showed increased TH (+7%) and phenylethanolamine N-methyltransferase (+16%) activities as well as an increased content of adrenal norepinephrine (+13%) and epinephrine (+21%). These findings demonstrate a genetic difference in the effects of a high-salt diet on the synthesis of catecholamines in the adrenal gland of Dahl R and S rats. Hypertension only occurs in S rats on a high-salt diet, concomitant with large increases in the formation of adrenal catecholamines.