A simplified method for the rapid isolation of cardiac intercalated discs.

A simple and rapid method for the isolation of intercalated discs from a single rat heart is described. The outstanding features of this method are (i) a large quantity of starting material is not necessary, (ii) ultracentrifugation and separating gradient steps are not required, (iii) the disc fraction is relatively pure as verified by electron microscopy, and (iv) the starting tissue is rapidly homogenized into buffer, reducing possible damage to membrane structures after animal death. The fraction is rich in intercellular junctions, with gap junctions, fasciae adherentes and maculae adherentes all appearing well preserved. It should prove a useful starting base for further purification of these junctions and of sarcolemma from a specific portion of the cell surface membrane, namely the major area of structural interaction between adjacent cardiac cells.