The Assessment of Tobacco Smoke Toxicity on Selected Tissues from the Cardiovascular and Respiratory Systems of the Albino Rat, an Ultrastructural Study

Abstract

Objectives: This work focuses on the effect of cigarette smoke exposure toxicity on the ultrastructure of selected albino rats’ cardiovascular and respiratory systems tissues from and their recovery within three months after exposure. Materials and Methods: Sixty male albino rats (Rattus norvegicus) were used in this study. Two groups, each consists of thirty rats. The first group was exposed to the cigarette smoke for three months on a daily basis, using a special modified smoking machine, while the second group (control) was left untreated. The exposure to smoking was followed by a period of three months of non-exposure to smoking as a recovery period. Following each period, the ultrastructural study was performed. Results: Cigarette smoke caused ultrastructural changes in the tracheal epithelium, heart ventricles and lung alveoli. Thin section of tracheal epithelium showed low number of cilia, a high degree of cytoplasmic vacuolization. Mitochondria aggregates in the apical portion of epithelial cells, inclusion bodies are present, and disrupted endoplasmic reticulums were also observed. The alveolar epithelium showed damaged multilamellar bodies of type II pneumocyte, together with cytoplasmic vacuolization and chromatin condensation, membrane blebs projecting from the cytoplasm, and degeneration of alveolar epithelium. The ventricular cardiomyocytes revealed mitochondria with deteriorated and partially disrupted or disappeared cristae. Also it showed areas with disrupted Z-discs. After the recovery period, those tissues showed partial recovery. Conclusion: Smoking induces ultrastructural changes in the respiratory passages and heart that affects the gaseous exchange and may predispose to cancerous changes due to accumulation of toxic and carcinogenic compounds, chromatin condensation and tissue inflammation. Cessation of exposure to cigarette smoking is important in returning most these changes to their normal ultrastructure.