Erythrocyte sodium ion transport system in DOC-salt, Goldblatt, and spontaneously hypertensive rats

Abstract

Altered erythrocyte Na⁺ transport has been observed in relation to the pathogenesis of essential hypertension. In the present study, intracellular Na⁺ and K⁺ levels, Na⁺-K⁺ pump activity, Na⁺-K⁺ cotransport, and Na⁺ passive permeability were measured in erythrocytes of DOC-salt hypertensive (DSH) rats, two-kidney, one clip Goldblatt hypertensive (2KH) rats, and spontaneously hypertensive rats (SHR). The results were as follows:

1. In comparison with the control groups, no change in the erythrocyte Na⁺ level was noted in the DSH and 2KH groups, whereas a significant increase was seen in the SHR group.

2. Although no change was noted in the erythrocyte K⁺ level in the 2KH and SHR groups when compared with the control groups, a significant decrease was seen in the DSH group.

3. Na⁺-K⁺ pump activity of erythrocytes was not changed in the DSH and 2KH groups when compared with the control group, but a significant increase was noted in the SHR group.

4. Na⁺-K⁺ cotransport of erythrocytes was not changed in any hypertensive rats when compared with the controls.

5. Na⁺passive permeability in the erythrocyte membrane was not changed in the DSH and 2KH groups when compared with the control groups, but a significant increase was noted in the SHR group.

These findings suggest that increased erythrocyte Na⁺ levels in SHR are due to increased Na⁺ passive permeability of the erythrocyte membrane, and increased Na⁺-K⁺ pump activity may be compensating for the increased intracellular Na⁺ concentration in erythrocytes. Furthermore, the increase in Na⁺ passive permeability observed in SHR might not result from hypertension itself but from abnormalities in the erythrocyte cell membrane, because no increase in Na⁺ passive permeability was noted in either DSH or 2KH rats.

Key Words:

• erythrocyte
• hypertension
• Na⁺-K⁺ contransport
• Na⁺ permeability
• Na⁺-K⁺ pump