Increased plasma immunoreactive atrial natriuretic factor concentrations in salt sensitive Dahl rats

We measured the immunoreactive atrial natriuretic factor concentrations in plasma and right and left atria of salt-sensitive, salt-resistant Dahl rats and Wistar Kyoto rats, all fed for 5 weeks by 8% salt diet. We found an increase in plasma immunoreactive atrial natriuretic factor (p less than 0.001) in salt-sensitive Dahl rats which became severely hypertensive in comparison with salt-resistant and Wistar Kyoto rats which remained normotensive on the same diet. There were however, no differences in the immunoreactive atrial natriuretic factor concentrations in the atria between the three groups of rats; all rats tended to have lower concentrations in the left than in the right atrium. The data show the presence of increased circulating atrial natriuretic factor immunoreactivity in hypertensive salt-sensitive Dahl rats which may be due either to the hypertension-induced left atrial distention, to volume expansion or indirectly renal hyposensitivity to the atrial natriuretic factor in these rats.