Development of in vitro calcium (Ca) transport in the spontaneously hypertensive (SH) and wistar Kyoto (WK) rat

Ca absorption is decreased in male SH rats at 5 and 12 wk. The authors studied intestinal Ca transport in 3, 4 and 5 wk old female rats, and 2) age of onset of the defect. The authors measured transport using everted duodenal sacs containing 40Ca (0.4mM) and 45Ca, suspended in a solution of the same composition and incubated 1 h. Serosal to mucosal concentration (S/M) ratio was lower in SH than WK at all ages studied. Since S/M ratio does not adjust for M to S water movement and weight of transporting tissue, the authors calculated 45Ca transport. This was lower in SH than WK at 4 and 5 wk, but was the same in both at 3 wk. Serum ionized Ca (mM) in older rats is lower in SH than WK (1.26 +/- +/- 0.02 vs 1.38 +/- 0.03, p < .05) but is the same in both at 3 wk (1.36 +/- 0.04 in both). The authors conclude that in female SH, decreased Ca transport is not present at weaning, nor is serum ionized Ca decreased. These defects develop in parallel with the reported increase in blood pressure