Effects of a high-salt diet on tissue noradrenaline concentrations in Dahl salt-resistant and -sensitive rats

1. We measured systolic arterial pressure (SAP) and tissue noradrenaline concentrations (tNA) of 16 organs (heart, kidney, aorta, brain stem, pancreas, spleen, stomach, jejunum, ileum, colon, lung, muscle, cerebrum, liver, bone, salivary gland) in Dahl salt-resistant (DSR) and -sensitive rats (DSS) fed 0.4 (0.4%) or 8% salt diet (8%) from 5 weeks old until the age of 5, 7, 9 and 11 weeks. 2. SAP increased in DSS with the 8% salt diet. An increased rate of SAP of DSS with the 0.4% salt diet was larger than DSR with the 0.4% diet. In DSR with 0.4%, tNA tended to increase from 5 weeks old except in the bone, which may have been the result of ageing. In DSS with 0.4%, tNA did not increase from 5 weeks old. DSS showed salt-sensitivity even to 0.4%. 3. tNA of the heart and kidney of both DSS and DSR with 8% were lower than 0.4%. These organs are high-salt-sensitive organs. tNA of the aorta, spleen, stomach, jejunum, ileum, and colon of DSS with 8% were lower than 0.4%, but not DSR. These organs are medium salt-sensitive organs. tNA of the pancreas of DSS with 8% was lower than 0.4% which was not different from DSR with 0.4 and 8%. The pancreas is a low salt-sensitive organ. tNA of the lung, muscle, cerebrum, liver, bone and salivary gland did not show any differences between 0.4 and 8% in DSS as well as DSR. These organs are not salt-sensitive organs. 4. There were large organ differences in tNA among organs studied. There were large organ differences in decrease rate of tNA in response to a high-salt diet. The organ function and the period of salt diet influence tNA.