Disturbance of Cholesterol and Bile Acid Metabolism in Spontaneously Hypertensive Rats (SHR)

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Abstract
Biliary secretion, fecal excretion, pool size, and turnover frequency of bile acids, as well as serum and liver lipid levels, were determined in spontaneously hypertensive rats (SHR) and compared with those in normotensive control rats (NR) of Wistar Kyoto strain. Serum cholesterol level in SHR was similar to that of NR but markedly increased after the feeding of a 2% cholesterol diet for one week. Liver cholesterol level in SHR was higher than that in NR for all ages (8 to 77 weeks) and markedly increased after cholesterol feeding. Bile flow and biliary secretion of cholesterol, phospholipid, and bile acids were markedly elevated in SHR. The cholic acid level was greatly increased but levels of other bile acids were not changed or even decreased. The blood pressure of our SHR started to increase at the age of 6 to 7 weeks and attained the maximum at 15 to 16 weeks. Bile flow appeared to increase with the development of hypertension. Fecal excretion of bile acids in SHR, in either total amount or bile acid composition, was not greatly different from that in NR. After cholesterol feeding, fecal excretion of bile acids increased more significantly with SHR. The pool size of bile acids, as well as biliary secretion, increased about 60% in SHR but the turnover frequency and bile acid synthesis were unchanged. It was concluded that the pool size of cholic acid was increased in SHR and that this enhanced the absorption of cholesterol, resulting in a marked accumulation of cholesterol in serum and tissues.