A theory concerning venom

-- If anyone thinks it would be worth it, I can move this to the sting reports section, since it concerns one --

A while ago I read a sting report on Centruroides sculpturatus published in the American Tarantula Society's Forum Magazine (16:1, 20-23). In it, a woman who was stung by C. sculpturatus attempted to numb the pain by submerging her stung hand in ice-water. Instead of numbing it, she described the pain as increasing exponentially.

I seem to recall seeing other cases where something similar happened: envenomated body part + ice water = significant increase in pain.

Now, here's where my theory comes in. The vast majority of scorpions have evolved venom for the purpose of incapacitating arthropod prey. Also, all scorpion venom (that I'm aware of) is composed primarily, if not exclusively, of small proteins (a.k.a. peptides).

My biochemical instruction has taught me that all proteins have an ideal activity temperature -- for example, when performing certain biochemical reactions in a laboratory setting, you have to keep your experiment at a specific temperature to get the maximum activity from whatever protein you may be using. Too hot, and it begins to denature; too cold and there's not enough free energy for it to perform.

Back to venom. If scorpions have evolved venom ideal for performing in an invertebrate system, then it stands to reason that the proteins involved would have maximum activity at the body temperature of the prey species. Humans, being endotherms, typically have a body temperature higher than the surroundings, while prey invertebrates would have body temperatures the same as their surroundings. Thus, it stands to reason that scorpion venom would be partially deactivated when in a human.

I also know that scorpion venoms are very stable -- they are small, so they can't unwind to the degree that a larger protein could, and they have disulfide bonds that serve to prevent them from unwinding. Thus, if such a protein were briefly heated above its ideal temperature, cooling it down would restore functionality (since its structure prevented it from being completely denatured).

What this all boils down to is that sticking your hand in ice-water brings your temperature down low enough that it increases the protein's activity, and thus makes it hurt a lot more.

This could also (partly) explain why scorpions from the hotter parts of the world have more potent venom -- proteins evolved to operate at a higher temperature may find themselves at their ideal temperature when in a human. (However, I know from flipping through The Biology of Scorpions that "hots" also have more complex venom glands, so activity temperature alone doesn't explain it.)

Thoughts?

amazingly well thought over... very interesting theory... probably deserves some in-depth research, but as far as i can think it makes sense...
does this mean that if you warmed up the sting area it could help to reduce it?

I agree completely with jordan, great theory.


so if you wanted to decrease the pain of the envenomation, you should raise the tempreture to a tempreture I high enough to denature the protiens? but wouldn't that mean sticking the affected area in boiling water?

why don't you try conducting an Experiment? I'm sure you could milk a scorp and try it out. (not on yourself lol)

A heat mat is worth a try . . .

And to warm up the affected area, boiling water would by no means be required. Body temp is 37C, boiling water is 100C. A nice toasty hot tub is only about 40C or so.

The problem is that once it leaves the heated area, it may regain some level of activity. Venom is disposed of by the lymphatic system so it *should* stop at your armpit. If it goes further you may be in trouble.

that would probably be a bit too far... there is probably a certain temperature that is the best to reduce the pain and after that will not make any difference.
of course it depends on certain things, if it was an emp sting then i wouldnt bother with putting ant part of me in boiling water. an LQ on the other hand... could be very useful to someone who has been stung in the desert or something and doesnt have access to medical help.

what about tarantulas?

I think it would work for T's venom too...are all venoms composed of protein?

then you have to consider venomous reptiles too... you could be on to something here!

Makes sense.

But remember Athlon also said that venom potency could do with he fact that certain species encounter a wider spectrum of predators.

spoze it wouldnt work the same for snakes as they eat mammals.

I don't know as much about T venom -- only a handful of species (mostly pokies) are worrisome enough to consider this, but I'm not sure what sort of peptides their venom is composed of.

scorpion111 wrote:

are all venoms composed of protein?

No -- some are composed of ions that interrupt nerve signals. Scorpion venom is neurotoxic as well, but it serves to block ion channels in nerve cells.

Cytotoxic venoms are usually protein-based, though. But as has been mentioned, some snake venoms are built to tackle mammal prey, so you're pretty much screwed if you get bit by one of those and don't have antivenom.

There's also hemotoxic venom (such as in that random scorpion species, and a few snakes) that probably serves to trigger the clotting signal cascade that normally only occurs when something damages the basement membrane in blood vessels.

I'll test this out. I'll try a mild venom sting that still causes SOME pain. Probably B.jacks or M. martensii. I usually wash my hands in warm water and have never experianced a really severe sting except for a C. sculpt but I went hiking in cold temps so that might have something to do with it.

would that random species be nebo sp.??? arent they in the same family as heterometrus?

Eddy, go for it. Get stung once on each hand; put one hand in hot water and one in cold water.

Although the scorpion may not produce the same amount of venom for each sting; do be scientifically rigorous, you're going to have to do it again a few days later and switch which hand gets which water (i.e., rep. 1: first sting = hot water, second sting = cold water; rep 2: first sting = cold water, second sting = hot water).

_scorpio_ wrote:

would that random species be nebo sp.??? arent they in the same family as heterometrus?

Yes.

I don't know.

Mr. Mordax wrote:

Eddy, go for it. Get stung once on each hand; put one hand in hot water and one in cold water.

Although the scorpion may not produce the same amount of venom for each sting; do be scientifically rigorous, you're going to have to do it again a few days later and switch which hand gets which water (i.e., rep. 1: first sting = hot water, second sting = cold water; rep 2: first sting = cold water, second sting = hot water).

Thats pretty much what i was planning and using the Discovery chanel way of getting a scorpion to sting so I get about the same amount of venom

that test whouldnt be vaild since Eddys system might react differnt to the venom in rep2, since it has been effected by it not so long ago..

Ah damn your right. Well it's been a while since I've been stung by a B. jacks or M. mart. Maybe a new species?

i belive for a test for this to be vaild you need like a 10 ppl test group or more. Then you test like ever orther person with 1 sp of scorpion and the rest with some orther scorpion then every orther uses hot water and rest cold. This give you a more general idea of what to do. But i bet that each sp have a differnt venom protien string ( Mike might know more of this then me or have better understanding ) that too will effect it allso..

Yeah, it's tough to estimate what proteins the scorpion will be releasing with each sting and in what quantities (since they can control it) -- i.e., I doubt a gravid female defending herself will produce the same quality of sting as a random male doing a defensive tail-flick.

Hmm . . .

- Take a variety of specimens of one "target" species -- we already have documented evidence of sting-cooling having an effect with C. sculpturatus
- Milk each species for "defensive" venom by provoking it to attack a dud probe that will collect venom (as "defensive" venom is typically what humans encounter, as opposed to, say, "prey immobilization"* venom)
- Using standard biochemistry techniques, separate the proteins found in the venom (probably using gel chromatography or similar)
- Pack each protein in a buffered saline solution and then use Kejser's method of the test group

This would allow you to find A) which proteins affect humans, and B) if the theory hold that cooling increases activity and / or heating decreases activity.

One caveat: this wouldn't pick up protein interactions; i.e., where more that one protein is required to have a medical effect in a test subject.


*However, prey immobilization venom would be even more specific to arthropods, and thus may confirm the experiment better . . .