Cardiac ultrastructural alterations in mice inoculated with Tityus discrepans (Buthidae) venom

In this work we have studied the cardiologic clinical manifestations appearing in response to toxic aggression by Tityus discrepans venom, such as hypertension, hypotension, tachycardia and pulmonary acute oedema. These depend on changes in the organisation of cellular and subcellular components of cardiac tissues and probably correspond with the damage found in envenomed humans. To evaluate cardiac tissue subcellular response to Tityus discrepans venom, male C57/B1 adult mice were randomised into two groups: envenomed mice were intraperitoneally injected at a dose of 5 mg/Kg of body weight and controls received saline solution. Samples from cardiac tissue were prepared for electron microscopy study and observed in a Hitachi-300. The most relevant cardiac ultrastructural findings in this model showed diffuse disarray of the myofibrils and abnormal pattern of the bands in the sarcomera, contractile element disorganisation, degeneration of fibres and loss of the characteristic sarcomeric structure given the appearance of a lax tissue. One of the most prominent features was the presence of a remarkable perinuclear oedema and the perinuclear cistern exhibited indentations over its whole arrangement. The vascular endothelium of the microvessels exhibited alterations with evident cytoplasmic projections toward the lumen of the vessel. Mitochondria presented a condensed conformation. All findings were degenerative signs of the contractile apparatus. We suggest that any cardiac tissue damage produced by toxins present in this venom are responsible for some of the clinical manifestations in envenomed animals and patients.