EFFECTS OF DIFFERENT TYPES OF ANTIAGING DIETARY RESTRICTIONS ON AGE-RELATED ATRIAL-NATRIURETIC-FACTOR CHANGES - AN IMMUNOCHEMICAL AND ULTRASTRUCTURAL-STUDY

The effects of two types of anti-aging dietary restrictions restrictoi ns - 60% diet restriction (DR) and every-other-day feeding (intermitte nt feeding, IF) - on age-related changes in atrial natriuretic factor (ANF) metabolism were studied in male Sprague Dawley rats by standard radioimmunological procedures and transmission electron microscopy. Bo th diet restrictions decreased plasma ANP (atrial natriuretic peptide) levels significantly (12-month-old rats: ad libitum fed controls 96+/ -17.3 pg/mL, IF 63+/-4.8 pg/mL, DR 74+/-14.4 pg/mL; 24-month-old rats: AL 109+/-6.3 pg/mL, IF 75+/-8.9 pg/mL, DR 65+/-9.1 pg/mL). Dietary re striction prevented the age-related increase in ANP concentration in b oth the right atrium (12-month-old rats: AL 0.25+/-0.033 mu g/mg, IF 0 .22+/-0.023 mu g/mg, DR 0.30+/-0.044 mu g/mg; 24-month-old rats: AL 0. 39+/-0.037 mu g/mg, IF 0.10+/-0.015 mu g/mg, DR 0.07+/-0.011 mu g/mg) and left atrium (12-month-old rats: AL 0.23+/-0.033 mu g/mg, IF 0.13+/ -0.019 mu g/mg, DR 0.17+/-0.035 mu g/mg; 24-month-old rats: AL 0.44+/- 0.037 mu g/mg, IF 0.07+/-0.009 mu g/mg, DR 0.07+/-0.011 mu g/mg). Endo crine cardiocytes of diet-restricted senescent rats could be readily d istinguished ultrastructurally from cells of ad libitum fed controls d ue to a higher number of beta-atrial specific granules of lower electr ondensity. In conclusion, anti-aging diet restriction regimens fully p revented the age-related increase in the hormone store in atrial tissu e, and lowered plasma ANP levels.