[Characteristics of the contractile reactions of rhythmically active vascular smooth muscles in spontaneously hypertensive rats undergoing hyperoxygenation and the role of the endothelium in their development].

Experiments on isolated preparations of the portal vein from healthy and spontaneously hypertensive rats have revealed that removal of the endothelium has no influence on hyperoxygenation-induced increase in the contractile activity of vascular smooth muscles (VSM). It is also shown that VSM from hypertensive rats demonstrate higher sensitivity to hyperoxygenation than VSM from healthy rats. Results of the study confirm a supposition that contractile effect of hyperoxygenation on VSM is realized mainly via direct influence of oxygen on plasma membranes of VSM and increase of the membrane permeability for extracellular Ca2+.