Effect of serum from spontaneously hypertensive rats on 86Rb washout in cultured vascular smooth muscle cells.

In addition to the known genetic abnormalities affecting the membrane permeability of vascular smooth muscle cells (VSMC) of spontaneously hypertensive rats (SHR), serum humoral factors may also play some role in the alteration of permeability of VSMC and possibly contribute to the pathogenesis of hypertension in SHR. To test this hypothesis, the passive K permeability described as the washout rate constant (Ke) was measured based on 86Rb washout from cultured VMC in response to serum from SHR, Wistar-Kyoto rats (WKY), and Wistar rats (W). Serum from the three rat strains produced a substantial increase in the Ke of 86Rb washout from 9.6 +/- 1.7 for the control (C) of 17.3 +/- 2.0 for SHR. 15.3 +/- 0.9 for WKY, and 16.0 +/- 2.4 for W (x 10(-3)/min) (p less than 0.001 comparing C with SHR, W and p less than 0.01 comparing C with WKY respectively). However, comparison of the Ke of 86Rb washout among the three rats strains revealed no significant differences. It is concluded that serum increased passive K permeability of VSMC in culture. However, the data do not support the suggestion that some unknown humoral factors in the serum from SHR are involved in the abnormal alterations of membrane permeability to cations and thus contributing to the pathogenesis of hypertension in the SHR.