Effect of chronic hypoxia on 45Ca and 86Rb uptake in aortic smooth muscle from spontaneously hypertensive rats (SHR).

The effect of chronic hypobaric hypoxia equivalent to a simulated high altitude of 4000 m was investigated on the Ca2+ and Rb+ uptake in vascular smooth muscle. The decline in systolic blood pressure in SHR due to hypoxia was associated with a significant decrease in 45Ca uptake and ouabain-insensitive 86Rb uptake as well as the tissue Ca2+ and K+ content. It seems likely that the reduction of the higher vascular tone in SHR by chronic hypoxia is due to the alteration of the transmembrane ion fluxes in the vascular smooth muscle cells. However, the meaning and the nature of the active and passive ion fluxes involved in this problem remains to be clarified.