Calcium and sodium transport in the duodenum of the Dahl salt sensitive and salt resistant rat.

We measured food intake, body growth and transport of calcium and sodium by duodenum of female Dahl salt sensitive (DS) and salt resistant (DR) rat strains. Food intake and body growth were similar for DS and DR rats taking both 0.4 and 8% sodium chloride diets. Food intake increased with age up to 5 weeks and then remained constant despite continuing body growth. Comparing DS and DR rats fed the 0.4% sodium chloride diet at 6 and 11 weeks or the 8% sodium chloride diet at 6 weeks, transport of calcium and sodium were the same in both the DS and DR groups. Transport of calcium, but not sodium, was lower at 11 than at 6 weeks. Comparing simultaneous feeding of either 0.4 or 8% sodium chloride diets to 6-week old DS and DR rat strains, transport of calcium tended to be lower in animals fed the 8% as compared to the 0.4% sodium chloride diet, and the difference was significant for net 40Ca transport for DR rats. The DS rat fed on 8% sodium chloride had higher systolic blood pressure (SBP) than the DR rat. We conclude that growing DS and DR rats, ingesting equal amounts of food, do not differ in duodenal calcium and sodium transport measured by the everted sac technique. The response to feeding sodium chloride differs between strains: the high salt diet decreases net 40Ca transport in the DR but not the DS strain.