[Ultrastructural changes in hepatocytes of mice treated with heroin]

In a study of the ultrastructure of a hepatocytes in mice treated with heroin a statistically significant increase in the volume density and surface density of smooth endoplasmic reticulum (SER) was observed. Morphometric measurements using the method described by Weibel (2,3) were employed to calculate volume density of smooth and rough endoplasmic reticulum and mitochondria, and surface density of rough and smooth endoplasmic reticulum membranes and of the mitochondrial envelope and cristae. Statistical analysis using the t test of Student was carried out for all parameters. Both surface density and volume density of SER in mice treated with heroin increased significantly when compared to mice of the control group. An increase in volume density of SER is generally believed to be correlated to an increase in drug metabolizing enzymes localized in or on smooth endoplasmic reticulum membranes. We have demonstrated a statistically significant increase in SER in mice treated with heroin which is not accompanied by an increase in drug metabolizing enzymes (7). We feel that further investigation of these anomalous cases is necessary in order to clarify the role of the SER membranes and their function in the metabolism of drugs.