Metabolism of lysolecithin by the perfused rat heart

Abstract

Lysolecithin prepared from biosynthetically labeled rat-liver lecithin was complexed with either whole rat serum or bovine serum albumin and was shown to be bound mainly to the albumin fraction. Isolated rat hearts showed a rapid uptake of lysolecithin labeled either in the phosphate or fatty acid moiety, and the extent of its uptake was proportional to the ratio of lysolecithin to albumin in the perfusion medium. Autoradiography of histologie sections of hearts labeled with [ 14C]- or [ 32P]-lysolecithin showed that the radioactivity was distributed diffusely and was not confined to the blood vessels. Hearts labeled with lysolecithin were reperfused with a medium devoid of protein and no loss of radioactivity from the heart was observed. When serum or bovine albumin were added to the reperfusion medium a major part of the lysolecithin could be eluted. Simultaneous labeling of the heart with [ 131I]-albumin and [ 32P]lysolecithin showed that the latter was taken up by the heart not as an albumin-lysolecithin complex. A part of the lysolecithin taken up by the heart was acylated to lecithin, a reaction which was progressive with time of reperfusion of a pulse labeled heart. In contradistinction to lysolecithin the labeled lecithin could not be eluted into a protein containing reperfusion medium. It is postulated that binding of lysolecithin to a tissue acceptor plays a part in the uptake of this phospholipid by the heart and that the lysolecithin might be involved in cellular membrane renewal.