The increase in viscosity and peroxidation of sarcoplasmic reticulum membrane lipids in isadrine myocarditis.

The viscosity of membranes isolated from sarcoplasmic reticulum of rabbits with isadrine myocarditis was studied, using pyrene as a hydrophobic fluorescent probe. The increase in the viscosity of membranes from injured heart occurred at lower temperatures and was sharper than in the case of intact heart in both "free" and "bound" lipid domains. The increase in the lipid viscosity under myocarditis was associated with decreased Ca++, Mg++ -ATPase and cAMP-dependent protein kinase activities and with an elevated content of lipid peroxidation products.