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Physiology of Stingray Venom

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Venom

- Optimum Conditions

Effects of Stingray Envenomation

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Optimum Conditions

Stingray venom is most toxic and most lethal at specific pHs and temperatures.  There is no evident venom potency difference in regard to different seasons or ages of stingrays (Russell et al., 1958). Hyaluronidase activity of stingray venom is highest at a pH of approximately 4.2 and a temperature of 37 degrees C as shown in the graphs below (Magalhaes et al., 2008).


Figure 1. pH versus activity of hyaluronidase in Potamotrygon motoro. Adapted from (Magalhaes et al., 2008).


Figure 2. Temperature versus activity of hyaluronidase in Potamotrygon motoro. Adapted from (Magalhaes et al., 2008).

 

 

The hyaluronidase lost 70% of its activity at 40 degrees C demonstrating that the venom can become inactive at higher temperatures. At 20 and 30 degrees C, the venom was stable for 30 minutes, however, when the hylauronidase activity was measured at 40 degrees C, there was a steady decline beginning in the first five minutes as seen in the graph below (Magalhaes et al., 2008).



Figure 3. Temperature stabillity of hyaluronidase acitivty from Potamotrygon motoro. Adapted from (Magalhaes et al., 2008).

 

Temperature-stability of hyaluronidase activity at different temperatures over 30 minutes.
At warmer temperatures, the venom’s biological effects on the victim are correspondingly more diminished.  Nociception, the perception of pain, and edema, swelling of soft tissue, are decreased with a subsequent increase in temperature as shown by the table below (Magalhaes et al., 2006).

 

Table 2. Effect of heating on biological activities caused by Potamotrygon stingray venom.  The venom was stored at certain temperatures and injected into mice to measure the effects.  The results are the mean of three experiments ± standard deviation with a p<0.05.  Adapted from (Magalhaes et al., 2006).

-70°C

RT

37°C

56°C

P. cf. scobina

Nociception (s)

130 ±25

111 ± 19

73 ± 12

48 ± 0.9

Edema (mm)

1.8 ± 0.4

1.6 ± 0.3

1.2 ± 0.3

1.0 ± 0.3

P. gr. Orbignyi

Nociception (s)

110 ± 31

100 ± 21

64 ± 13

43 ± 8.0

Edema (mm)

1.7 ± 0.3

1.5 ± 0.4

1.2 ± 0.2

0.9 ± 0.1

 

When dealing with time, less lethal extracts of stingray venom lose their toxicity faster than more lethal extracts.  Also, at lower temperatures, the venom exhibits a slower rate of toxicity lost.  Undisturbed venom frozen at -20°C can remain lethal for a period of at least 12 months while saline extracted venom in 26°C temperature will become inactive between 4 and 18 hours later (Russell et al., 1958).

 

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