Unusual Mobility of the Elastic Protein Titin in Thirteen-Lined Ground Squirrel Hearts

Abstract

Small mammalian hibernators, such as thirteen-lined ground squirrels, undergo rapid, 100-fold reductions in heart rate, leading to a substantial prolongation of the cardiac cycle when entering torpor. Initial studies using high Urea solubilization buffers and Vertical Agarose Electrophoresis suggest no seasonally dependent change in the ratio of the longer, compliant N2BA to the shorter, stiff N2B cardiac titin isoform (N2BA:N2B). However, an unusually large protein was observed. Previously, this band was observed in preparations using urea-free solubilization buffers and agarose-acrylamide gel systems.