A greater stimulation of vascular smooth muscle cell proliferation by serum from spontaneously hypertensive rats

In an attempt to delineate the differential characteristics of serum from hypertensives on the proliferation of vascular smooth muscle cells (VSMC), we compare the effect of serum from spontaneously hypertensive rats (SHR) with that from normotensive Wistar-Kyoto rats (WKY) in its ability to stimulate proliferation in VSMC. Cell number determination showed that 10% serum from either of the two strains substantially stimulated proliferation of serially passed cultured VSMC, the effect being significantly greater with SHR serum than with WKY serum. 3H-thymidine incorporation into newly synthetized DNA was also tested after treatment with 10% SHR or WKY serum. A substantial increase in the uptake was noted in response to the rat serum, the effect tending to be greater with SHR serum than with WKY serum. No difference was found between the two strains in cell size determined as intracellular water volume. These data provide the evidence of an increased growth stimulating activity of SHR serum. This abnormality may be superimposed on the already-known innate hyperproliferative capacity of VSMC of SHR, leading to an increase in the deterioration of vascular complications seen in this model.