6-Hydroxydopamihe, Norepinephrine Depletion, and the Ultrastructure of Cardiac Muscle

Abstract

We have previously found that two drugs which alter tissue concentrations of biogenic amines also induce changes in the ultrastructure of cardiac tissue in active bats. Reserpine, which depletes stores of norepinephrine (NE) and 5-hydroxytryptamine (5-HT), leads to an increase in size and number of lipid droplets and glycogen granules, major structural changes in mitochondria and dilatation of the T-system. Parachlorophenyl-alanine which did not deplete NE but did deplete 5-HT by interfering with its biosynthesis, mimicked the action of reserpine on the lipid droplets of cardiac muscle but did not produce mitochondrial changes. This suggested that the changes in lipid droplets could not be related to cardiac NE. However, the other changes in cardiac ultrastructure that followed administration of reserpine could have been so related.