Effects of dietary lipids on frequency and force in atrial muscle at 10 MPa.

Spontaneously beating atrial preparations, from rats fed different lipid diets, were compressed to 10 MPa. The following observations were made: Different lipid diets altered the ratio of omega-6/omega-3 polyunsaturated fatty acids of the cardiac phospholipids. Beating frequency and twitch tension at surface pressure was unaffected by the diets. Compression to 10 MPa caused a decrease in spontaneous beating frequency and an increased twitch tension in all preparations. The decrease in beating frequency was inversely related to the omega-6/omega-3 ratio. Pressure induced increase in twitch tension was not affected by the diets. N2O dissolved in the tissue bath solution partly counteracted the pressure-induced changes.