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Physiology of Stingray Venom
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Stingray venom can induce many cardiovascular effects on the victims' bodies. These effects include neurotoxicity, cardiotoxicity, and circulatory disturbances (Magalhaes et al., 2006; Dehghani et al., 2009). The venom acts directly on the cardiovascular system and has been known to cause complete and irreversible cardiac standstill. In high venom concentrations, arterioles, veins, and large arteries may vasoconstrict in repsonse to the venom (Germain et al., 2000). Low venom concentrations may cause the cardiovascular system to exhibit simple vasodilation or vasodilation followed by vasoconstrction (Russell et al., 1958). Such vasodilation and vasoconstriction has been shown to occur through experimentation on cats. These effects thus result in changes in blood pressure and cardiac output (Dehghani et al., 2009).
The venom can further cause coronary artery spasms, chest pain, and changes in the heart's electric activity. Specifically, envenomation can cause an atrio-ventricular block for about 30 seconds along with changes in the amplitude of the systole and an increase in heart rate (Dehghani et al., 2009). Below is a graph of the heartbeat in mice injected with 100 µg of Himantura gerrardi epithelium extract.
Figure 5: Heart rate at differing time intervals: before (control) and 0, 2, 20, and 40 minutes after injection of 100 µg of Himantura gerrardi epithelium extract. Values are mean ± SEM (n=6). *Significant using a p<0.05 when compared to control. Used with permission from (Dehghani et al., 2009).
Furthermore, the changes in amplitude of the systole combined with an increase in heart rate results in changes in the RR interval of the heart. Q and T waves are also altered along with a decrease in PR intervals (Dehghani et al., 2009). Below are ECGs of PR intervals, RR intervals, Q waves, and T waves.
Figure 6: Changes in ECGs (voltage versus time) of mice injected with Himantura gerrardi spine epithelium extract: A (before), B (after 20 minutes), and C (after 40 minutes). Used with permission from (Dehghani et al., 2009).
Topics in Animal Physiology