A hypertensive substance in erythrocytes of spontaneously hypertensive rats

The effect of the subcutaneous injection of plasma or erythrocytes on the blood pressure of Sprague-Dawley (S-D), Wistar-Kyoto (WKy), and spontaneously hypertensive (SH) rats was examined over a 3-week period. The injection of plasma produced no detectable alteration in blood pressure in either the normotensive or hypertensive strains. The injection of red cells from WKy rats had no effect on the blood pressure of S-D rats, whereas a moderate (20%) elevation was noted in WKy and SH rats which received erythrocytes from S-D and WKy rats, respectively. The injection of red cells from SH rats produced no effect on S-D rats, a moderate (20%) elevation of the blood pressure of WKy rats, and a marked (42%) increase in the blood pressure of SH rats. Despite the lack of effect of erythrocytes on the resting blood pressure of S-D rats, it was found that these animals exhibit a transient increase in the blood pressure response to norepinephrine (NE) following a single injection of SH red cells. The results suggest the presence of a substance in SH erythrocytes which enhances the pressor response to NE and produces an elevation of resting blood pressure. This substance also appears to occur to some extent in the red cells of S-D and WKy animals; the manifestation of its action on blood pressure elevation is determined to a significant degree by the intrinsic resistance or susceptibility of the animal.