[Function of the rabbit myocardium sarcoplasmic reticulum and the resting potentiation of isolated trabeculae following cholesterol-oil feeding].

It is assumed that the resting potentiation of contraction corresponds to the Ca accumulating activity of the sarcomplasmic reticulum (SR). To test this supposition, resting potentiation and Ca transport by isolated microsomes of the heart were compared. The experiments were done in isolated trabeculae and in hearts of rabbits which had received a lipid-rich diet for 12 weeks. Preparations of control animals were used for comparison. Resting potentiation of the isometric contraction as well as Ca binding and Ca uptake were enhanced by the lipid-rich diet. The results confirm the strong relation between the resting potentiation of contraction and the Ca accumulating activity of the SR. The increased Ca transport may be related to differences in the lipid content of SR membranes.