Altered permeability of the erythrocyte membrane for sodium and potassium ions in spontaneously hypertensive rats

Abstract

Permeability of the erythrocyte membrane for sodium and potassium ions was studied in 8–10-week old spontaneously hypertensive rats (SHR, Kyoto Wistar strain), normotensive Wistar and Sprague-Dawley rats. The rate constant of Na/Na exchange was considerably greater in the SHR than in the normotensive Wistar and Sprague-Dawley rats. This difference remained the same in the rats adrenalectomized 7 days prior to the experiment. The maximum difference in the constants was found when the sodium pump was blocked by ouabain. The accumulation of⁴²K in the erythrocytes of the SHR (the sodium pump being blocked) took place at a considerably slower rate, and the K⁺ washout into a potassium-free medium was faster than in the normotensive Wistar and Sprague-Dawley rats. These results seem to indicate a higher permeability of the SHR's erythrocyte membrane for Na⁺ and K⁺ions, as compared to normotensive Wistar and Sprague-Dawley strains. It is suggested that the increased permeability of the erythrocyte membrane for Na⁺ and K⁺ in the SHR may reflect a more widespread cell membrane defect, which could serve as a general cause for activating the mechanisms maintaining high blood pressure.