The feeding with unsaturated fatty acids modifies the course of the isometric contraction of rabbit papillary muscle in hypoxia.

Alterations of cardiac membrane functions can be induced by lipid rich diets. As to this the influence of the admixture of cholesterol (group Ch) and rape oil (group R) to standard food during 12 weeks on the course of the isometric twitch of rabbit papillary muscles in normoxia and hypoxia was studied. In group R the rate of contraction and relaxation is enhanced. This points to alterations in the role of the sarcoplasmic reticulum (SR), most probably due to the incorporation of unsaturated fatty acids. During hypoxia at 4 mM Ca concentration the force is more decreased in group R than in the control group C, but the rate of the contraction remains higher. The relaxation is more impaired especially in the early phase. The load-length relation is shifted to the left. The influence of hypoxia in group Ch was similar to group C. The results are hints for the Ca overload of the cells, preferentially in group R. The SR function seems to be more damaged, f.i. by radicals reacting with unsaturated fatty acids and by Ca activated lipolyses.