Effect of reduced food intake on blood levels of a hypertensive factor in spontaneously hypertensive rats.

We have previously demonstrated the existence of an active component(s) of extracts prepared from rat erythrocytes that stimulates the in vitro uptake of calcium in aortic rings and induces a sustained elevation in the blood pressure of normotensive rats. The apparent concentration of the calcium stimulatory component and the responsiveness of aortic rings to stimulation of calcium uptake by the compound is exaggerated in adult spontaneously hypertensive rats (SHR) compared with normotensive controls. Although no effect was observed on tissue responsiveness to the compound, a decrease in the concentration of the compound was observed in the blood of adult SHR subjected to dietary manipulation designed to blunt the elevation of blood pressure. These data suggest that blood concentration of the active compound may be influenced by external stimuli such as dietary manipulation.