[Diet-induced changes on Ca-regulation in rabbit papillary muscle. 2. Contraction, relaxation and rest...

To characterize consequences of rape oil-induced changes on the Ca regulation in rabbit papillary muscle, the influence of increasing extracellular Ca (Cae) on contraction, relaxation and resting potentiation of tension has been investigated after a 12 weeks lasting rape oil-diet. After oil diet increasing Cae caused a similar augmentation in peak tension T accompanied by an increased index in contractility [Formula: see text], a significantly shortened time to peak tension and a decline in refractory period. A higher relaxation rate is demonstrated by the maximum relaxation rate [Formula: see text], the half time of relaxation RT 1/2 and relaxation time RT. The resting potentiation of the isometric contraction was enhanced. The results are in agreement with the assumption that the sarcoplasmic reticulum (SR) is more involved in Ca regulation after the oil diet than in the control group. This may be related to differences in the phospholipid content of SR membranes.