Amir Vazirizadeh

The upside-down jellyfish produces venom with some biological activities. In the present study, direct cardiotoxicity of crude tentacle-only extract from the Persian Gulf jellyfish ‘‘Cassiopea sp.” was assessed by a Langendorff isolated perfused rat heart system. Treatments were performed with concentrations of 50, 20, 10, 5, and 2.5 lg/ml of crude tentacle-only extract (CTOE) on isolated rat hearts for 60 min. Then, the hemodynamic parameters of heart rate, left ventricular end-diastolic pressure, left ventricular systolic pressure, left ventricular developed pressure, and coronary flow were evaluated. Lactate dehydrogenase (LDH) levels as well as histopathological examinations were also investigated. Based on the ECG findings, treatments in a dose-dependent pattern changed cardiac electrical activity and decreased coronary effluent. The higher concentrations of CTOE produced severe bradycardia, atrioventricular dissociation, complete atrioventricular block, and ultimately cardiac arrest. Ventricular end-diastolic pressure was also significantly increased by high concentrations of CTOE. At high CTOE concentrations, scatter lymphocytic infiltration and wavy fibers were found in the histopathological examinations. Treatment with concentrations of 2.5–10 lg/ml caused a considerable increase in LDH levels within 30 min compared with baseline levels. In conclusion, CTOE from the Persian Gulf upside-down jellyfish had significant direct cardiotoxicity effects on isolated rat hearts.