Serum aldosterone and protein-binding variables in Yanomama Indians: a no-salt culture as compared to partially acculturated Guaymi Indians.
Yanomama Indians from the jungles of southern Venezuela and northern Brazil excreted 1 +/- 1.5 mEq of Na and 203 +/- 109 mEq of K and had low blood pressure (BP), 102/62 mm Hg). In comparison, Guaymi Indians of Panama excreted 103 +/- 50 mEq of Na and 118 +/- 52 mEq of K and had significantly higher BP (114/75 mm Hg, p less than 0.001). Elucidating the renin-aldosterone axis, total upright serum aldosterone in 34 Yanomama was high (85.6 +/- 78 ng/100 ml). The binding capacities of thermolabile (ABG) and thermostable (ABG-Ts) serum globulins for aldosterone were elevated at 23.8 +/- 6 and 14.9 +/- 2.6%, respectively; consequently, total ABG- plus ABG-Ts- bound aldosterone was as high as 38.6 +/- 6.3%. Plasma renin activity (PRA 10.3 +/- 2.4 ng/ml/h) and urinary aldosterone 18-glucuronide (70.3 +/- 30 micrograms/24 h) in 17 Yanomama were also very high. In contrast, total serum corticosteroids and corticosteroid-binding globulin (CBG) binding capacity were normal, suggesting normal ACTH activity. PRA correlated positively with total (r = 0.47, p less than 0.05) and free (r = 0.47, p less than 0.05) serum aldosterone, which in turn showed a negative trend with Na (r = 0.33, NS) excretion. The effect of high dietary K appeared less important to aldosterone stimulation and PRA suppression. ABG-bound aldosterone (r = 0.43, p less than 0.01) as well as ABG-Ts (r = 0.56, p less than 0.05) were negatively correlated with diastolic but not systolic BP. The total ABG- and ABG-Ts-bound fraction correlated with diastolic BP (r = 0.43, p less than 0.05) in contrast to the free fraction (r = 0.08, NS) or total aldosterone (r = -0.09). Apparently, only bound serum aldosterone is important for the maintenance of diastolic BP. High serum aldosterone, with elevated excretion, indicates an increased secretion rate; increased serum protein binding suggests an increased tissular activity and alterations in aldosterone metabolism. In Guaymi Indians both total plasma aldosterone (14.5 +/- 65 ng/100 ml) and urinary aldosterone (8.1 +/- 4.8 micrograms/creatinine excretion) were normal. ABG-binding capacity for aldosterone was moderately elevated (17.8 +/- 4.8) and of ABG-Ts normal (10.2 +/- 1.2) suggesting a nearly normal aldosterone metabolism and regulation. The BP of Guaymi was significantly higher than that of the Yanomama.
D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000097:blood; D000328:Adult; D000450:Aldosterone / Q000031:analogs & derivatives / Q000097:blood* / Q000652:urine; D001667:Binding, Competitive; D001794:Blood Pressure; D001938:Brazil; D002352:Carrier Proteins / Q000097:blood*; D003971:Diastole; D004039:Diet, Sodium-Restricted; D005260:Female; D006801:Humans; D007197:Indians, Central American; D007199:Indians, South American; D008297:Male; D008875:Middle Aged; D010176:Panama; D011188:Potassium / Q000652:urine; D012083:Renin / Q000097:blood; D012712:Serum Globulins; D012964:Sodium / Q000652:urine; D013599:Systole; D014156:Transcortin / Q000032:analysis; D014687:Venezuela
D000305:Adrenal Cortex Hormones; D002352:Carrier Proteins; D012712:Serum Globulins; C018447:aldosterone 18-glucuronide; D000450:Aldosterone; D014156:Transcortin; D012964:Sodium; D012083:Renin; D011188:Potassium