ALTERED PERMEABILITY OF ERYTHROCYTE-MEMBRANE FOR SODIUM AND POTASSIUM-IONS IN SPONTANEOUSLY HYPERTENSIVE RATS

Permeability of the erythrocyte membrane for Na+ and K+ was studied in 8-10 wk 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 Na pump was blocked by ouabain. The accumulation of 42K in the erythrocytes of the SHR (the Na pump being blocked) took place at a considerably slower rate, and the K+ washout into a K-free medium was faster than in the normotensive Wistar and Sprague-Dawley rats. These results seem to indicate a higher permeability of the SHR erythrocyte membrane for Na+ and K+, as compared to normotensive Wistar and Sprague-Dawley strains. 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.