MILK ELECTROLYTE CONTENT OF DAHL HYPERTENSIVE AND NORMOTENSIVE RATS

Milk samples were collected from lightly anesthetized lactating female rats of the Dahl hypertension-sensitive (SS/Jr) and Dahl hypertension -resistent (SR/Jr) inbred strains on postnatal days 8, 14 and 18. Thes e milk samples were stored at 4 degrees C until analyzed for content o f calcium (Ca++), magnesium (Mg++), chloride (Cl-), potassium (K+), so dium (Na+), and total protein. Our findings revealed that milk samples from females of the two strains were remarkably similar in content of electrolytes and total protein at each of the three sampling times. T he only significant difference from among a total of 18 strain compari sons across the three sample times was that milk levels of Ca++ were s ignificantly higher in SS/Jrs compared to SR/Jrs on postnatal day 14. These findings clearly indicate that these milk constituents do not di ffer between mothers of the two Dahl strains. Thus, milk concentration s of electrolytes and protein do not appear to serve as an environment al stimulus during the preweanling period for the dramatic age-related increases in arterial pressure characteristic of the SS/Jr strain.