[Effect of increasing the osmolarity of the extracellular medium on conduction, contractile responses and ultrastructure of vascular muscle].

Increased osmolarity of extracellular milieu suppresses spontaneous contractions of the v. porta smooth muscles first due to disturbance of excitation conduction among the cells necessary for rhythmic contractions of the muscles. Further suppression is due to decrease in the rhythmic electrical activity of the spontaneously active pace-maker smooth muscle cells (SMC). Increased osmolarity alters the SMC reactive ability: their responses to noradrenaline and acetylcholine become less obvious. Increased osmolarity induces lesion of the intercellular contacts, wrinkling of the cells and disorder in the structure of cellular membranes.