Atrial natriuretic factor release in cardiomyopathic hamsters

Studies were done in male cardiomyopathic and normal hamsters to examine the effect of heart failure on atrial natriuretic factor (ANF) secretion. Five groups of animals were studied. The hamsters were 70, 150, 200, 250 and 300 days old. The degree of heart failure became more severe with age. This was associated with a marked increase in left and right atrial weight. Plasma ANF rose in the cardiomyopathic hamsters with age, and no significant change was seen in the normal animals. ANF levels in the atrial tissue declined as the animals developed heart failure, suggesting that ANF release increased in heart failure. To examine these directly, the right and left atria of these animals were isolated and superfused in a modified Langendorff apparatus. The effluents from these experiments were collected and analyzed for ANF levels. Analysis showed that ANF secretion (expressed as pg/min/mg of tissue) declined in heart failure. Since there were significant atrial hypertrophy, the results were also expressed as picogram per minute per atrium. When the data were shown as picogram per minute per atrium, there was a marked increase in ANF secretion. The present data show that one of the factors causing an increase in circulating ANF in heart failure is augmented secretion.