Effects of Some Vasoactive Agents on Isolated Blood Vessels from Cholesterol-fed Rabbits
1975 Volume 23 Issue 3 Pages 515-520
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1975 Volume 23 Issue 3 Pages 515-520
The effects of several vasoactive agents on the blood vessels from cholesterol-fed rabbits were investigated. Fourteen rabbits fed with cholesterol-containing pellets (2% cholesterol and 6% corn oil) showed an increase in a total blood cholesterol level up to 1142±98mg/dl in three months. Various macroscopic changes in the blood vessels and other tissues of cholesterol-fed rabbits were observed at the end of three-month feeding, e.g., fat deposition in the subcutaneous tissue of ear and iris, atheromatous plaques in the intima of thoracic aortae and fatty livers. In the isolated hearts, there was no significant difference between cholesterol-fed and control animals in coronary vasodilatation caused by glyceryl trinitrate, 5μg/ml, and papaverine, 10μg/ml. The perfused central ear arteries from cholesterol-fed rabbits showed a tendency to be less sensitive to norepinephrine, 10-9-10-5, histamine, 10-9-3×10-5 and KCl, 3×10-3-3×10-1g, than those from control animals. In aortic strips from cholesterol-fed rabbits, norepinephrine, 3×10-9-3×10-5, angiotensin, 10-9-3×10-5 and BaCl2, 3×10-5-10-2g/ml, caused greater contractions than in the controls. On the contrary, histamine, 10-8-3×10-4, and KCl, 7.5×10-4-2.2×10-2g/ml, induced smaller contractions in the atherosclerotic aortae than in the controls. The descending aortae were generally more sensitive to the agents than the ascending aortae. Such various changes suggest that the atherosclerotic development in the blood vessels influenced either favorably or unfavorably on the contraction of the smooth muscle depending on the agents, although its detailed mechanisms need further investigations.
