The Venon:

In the snakes, the venon, along with the eyeteeth designed perfectly for the injection of the same, represents an evolutionary advance important to hunt and to initiate the digestive process of the prey, which in addition can be used like defense mechanism.

The venon of the snakes is a viscous liquid of yellowish color or is transparent. One treats, basically, of a type of chemically very complex saliva with great variety of enzymatic and farmacológics activities, being considered like one of more complex oral secretions of the vertebrates. Like secretion, besides immobilizing the prey, its activity initiates the digestive process of weaves of the victim before arriving at the stomach. It is formed by 20 to 30% of biologically active solid parts, mainly proteins with enzymatic activity. The 70 to 80% of the water serve like vehicle of the solid parts.

Each venon is a toxin combination that acts jointly. Its composition varies between individuals of the same species and, in some cases, within the same litter. The geographic surroundings and the season of the year create regional differences in the composition of the protein fractions of venons. The variation is greater between separated populations geographically.

For example, the common rattlesnake (Crotalus durissus cumanensis) of most of the country is predominantly neurotoxic, nevertheless, the units captured in the neighborhood of Los Teques and piedemonte of the Cordillera de la Costa that goes towards the Guaira, are frankly hemorrágics, besides neurotoxic.

Another example related to the differences in venons of this species is in the major or minor degree of presence of the crotamina (another type of neurotoxina). Geographic zones exist where the crotamina shows an ebullient clinic whereas in others she is little, originating few manifestations.

The size of the glands is related directly to the size of the snake and of it is deduced easily, that the venomous snakes are much more dangerous when reaching their adult age by this we do not have more to neglect with these same ones in youthful state already with are equally dangerous and mortal.

In varied studies sample that have been isolated near 30 different enzymes from these venons. Most frequent they are the enzymes with proteolytic activities and fosfolipasas.

The proteolytic enzymes/metaloproteinasas can destroy of titular proteins, alter the coagulation system and favor the activity of other enzymes. For example, the collagenases act on the tissue colágeno and, next to hialuronidasa, they dissolve intercellular unions, increasing the diffusion of the poison through weaves. An example of these enzymes is the hemorraginas, that as much cause damage to the vascular endothelial lining in the site of injection like in distant organs, causing bleeding. On the other hand, the procoagulating enzymes /anticoagulantes have different factors that act the factors of the coagulation, giving like final result sanguineous incoagulability. Among them are the enzymes with activity similar to the thrombin, which turn the fibrinógeno to fibrinopéptidos, the activadoras enzymes of the factor X and others If we united these two last enzyme groups (hemorraginas + anticoagulating procoagulants/) we obtain a serious clinical picture of profuse bleeding by destruction of the blood vessels without the capacity to stop bleeding and to repair themselves to if same.

The rest of enzymes can digest almost any tissue material, as it is to be expected, of digestive enzymes: ribonucleasas, nucleotidasas and deoxirribonucleasas.

Fosfolipasas can act like neurotoxinas (crotoxina in South American rattlesnakes and neurotoxinas of corale venons), which are of great toxicity and like miotoxinas which markedly bring about destruction of structural membranes of weaves of the prey, damaging the skin and the muscles, as well as internal organs of the prey. The neurotoxinas (the toxic of the nervous system) interfere with the mechanisms of nervous transmission, at sináptic level post (neuromotora plate) and/or at presináptic level, causing muscular paralysis which can take to a severe respiratory fault.

Altogether, the action of toxins causes generalized alterations of the cellular metabolism, taking to the death of the victim.

All the present substances in venons are not enzymes, because also they present/display polypeptides, glycoproteins and toxic elements of low molecular weight (colubridae). The roll of these substances is at the moment being defined.

The venon of the snakes does not have a constant composition throughout its life; there are manifolds factors that modify like the age, length, weight and sex of the snake cause that there is variations in the amount and quality of his venon. While more young person is the animal his venon has more neurotoxic and hemorragic tendency to be, for the fast paralyzation of the prey (mainly reptiles) avoiding an intense fight. However, the adult snakes have venons with greater proteolytic activity to promote a greater digestive efficiency, dice to that their main food is the rodents.

Other factors can condition the quality of the venon like the health state. The ill snakes produce minor amount of venon and this one is of bad quality, even, in many cases, have a contained snot major. In posprandial state the snakes have minor amount of venon, because it leaves from this one was used in the prey. One has determined that the prolonged fasting (hibernation) affects the composition of the venon and highly makes the bite dangerous of a unit in poshibernation state.

Nowadays, due to the advances in science, the venons can be classified according to their chemical properties like enzymes and their different biological activities, like toxins.

It is important to emphasize that the toxic activity of a specific protein within a poison can be caused or not by its activity like enzyme. To an enzymatic activity one talks about strictly to his chemical activity on other molecules like proteins (colagen, fibrin, fibrinógeno, thrombin), phospholipids, sugars, nucléicos acids), independent of if that enzymatic activity is responsible or not for the venomous effect like component of the venon.

A biological activity talks about strictly to the venomous effect (fisiopatologic) of the venon on the organism (procuagulants/anticoagulating, necrosants, desfibrinant, neurotoxic, cardiotóxics, etc.). For example: fosfolipasas A2 (denomination biochemical - enzymatic of that protein) can be, according to the type of serpent produces that it, neurotoxic or miotóxica (necrosante). The first activity strictly does not depend on its biochemical property to break phospholipids of the cellular membrane… but in second, it is its ability to break the membrane of the cells which makes necrosant.

The power of a poison is expressed like the lethal dose, that represents the smaller amount of poison than to have to be administered in an organism to kill it. Generally, in toxicology the lethal dose 50 is used (LD50), that represents the dose able to kill to 50% of the animal of experimentation in a period of certain time. To smaller LD50, major power.

As it can be appraised, the snakes have the capacity to produce lethal envenomations. there is a direct relation between the size of the snake and the amount of venon that produces (to so large major more venon), being the bells the one of greater potential danger by the great production and discharge venon lethality.

Nevertheless, it is even known that when a snake attacks not necessarily it releases all the venon of his glands, being able to be able of not unloading venon. They have great control on the liberation of the venon when the attack is defensive, which does not discard the possibility of a total unloading of his venon glands when very they are irritated.

The venons of the snakes, have been very studied from the chemical point of view and it has been that many of the substances conform that it, and that present/display a noticeable toxic activity, can be used, once separated totally of the venon, like therapeutic products for the treatment of certain diseases.

This demonstrates the importance that has the venomous snakes since without his venons it would be more difficult to obtain these products for the medical use. Apart from which also they comprise of the natural controls of rodents (rats and mice) that constitutes a true plague and danger for the health of the inhabitants of the countryside.

The venon is totally innocuous (inoffensive) to the tact, as long as the skin is totally healthy.
(Lee Ch.,1991).

The Distribution of poisons varies according to the family who treats: If the poisons of the serpents of the family Viperidae - Crotalinae study, it is that it has preference to be accumulated in lungs, heart, thymus, kidneys, liver and thyroid. On the other hand, the poisons of the Elapidae Family tend to be accumulated in renal crust, liver, spleen and lungs. (Lee, Ch., 1991).

Pharmacology of the Envenomation:

The Necrosis:

The word necrosis means “quickly happened cellular death produced by toxins or insufficient sanguineous irrigation (ischemia). In the case of venons of the snakes, the necrosis happens for both reasons. Enzymes exist that are in charge to destroy to the cells, calls necrosantes enzymes which own chemical activity of the proteolytic type (“which they break proteins”). They are spread very in mapanares and less proportion in the bells. They are the main cause of the severe local pictures that appear the botropics accidents. The necrosis is pronounced concerning skin, muscles, cartilages, routes sanguineous and organs like lungs, liver and kidneys.

A severe and chronic necrótic picture
it can let irreparable sequels in a bite being able happen from putting out of action or loss
of the member affected until the death. The second cause of necrosis is an insufficient one
sanguineous irrigation due to the alteration of the integrity of the sanguineous routes, which
the volume of blood falls that arrives at the affected zone.

The Hemorrhage:

It is defined as hemorrhage to the continuous bleeding caused by alteration (rupture) of the routes sanguineous.

It was already mentioned that the necrosants enzymes destroy to the weaves and that one of the affected ones are those that conform to the sanguineous routes.

Another cause of favors bleeding will be mentioned when the alterations treat in the sanguineous coagulation. It can affect lungs, mesenterio and internal and bring diminution of the arterial pressure consequently (hypotension) and necrosis.

The Hemolisis:

One of the signs that are mentioned in some texts on bites of snakes is the hemolisis.

This deals with the rupture of the wall of red blood cells because of the enzyme action certain that is in venons of the snakes.

The rupture of red blood cells consequently brings a severe diminution of the oxygen transport towards the cells and on the other hand, obstruction of the kidneys.

It is important to make clear that one has demonstrated that the venons of the snakes do not induce direct hemolisis.

That is to say, that these do not break to red blood cells under normal conditions of health.

Studies have demonstrated that this has only been observed in patients who suffer of hipoalbuminemia, a disease that is pronounced in people with bad nutrition (Tu, A, 1977).

In addition, in tests with animal of experimentation dealt with rattlesnakes it was observed that obtained the healthy animal red blood cell levels were similar to the levels found in animal injected with the poison (López, J.J.C.,1999b)

The Neurotoxics:

The term talks about enzymes of the venon that affect the transmission of nervous impulse a
peripheral level, that is to say, on the nervous completions that arrive at muscles.

Of this form muscle paralyzes happen certain such as the diaphragm and the intercostal ones; muscles of neck, language, eyes and until can take place alterations by increase of salivary, lachrymal and bronchial secretions.

The gravity of the picture is consequence of the association of effects and death happens by respiratory paralysis.

The Edema:

It is defined as edema to the swelling that is observed as a result of the accumulation
of liquid in the space outside weaves.

It must to an increase of the hair permeability and
it comes accompanied by local pain and diminution of the arterial pressure.

The increase of the hair permeability is product of the activity of the enzymes of the venon, which diminish the capacity of the capillaries to retain the liquid.

The diminution of the arterial pressure is, also, consequence of the loss of the circulating sanguineous volume due to edema and by increase of the thickness of the blood vessels.

Alterations on the Coagulation:

This he is one of the effects, observed sistémic level, that causes to majors complications
for the recovery of the patient.

The final picture that is developed is what is called one Scattered Intravascular coagulation (C.I.D.).

When taking place rupture of some of the blood vessels, immediately, triggers a series of chemical reactions within the blood, that take to the formation of the clot that will plug the rupture avoiding the bloodshed.

Within the enzymes that are in venons of the snakes exist some, that when being in the sanguineous torrent, they trigger the chemical reaction that induces the formation of clots of uncontrolled form.

A second enzyme group exists that instead of to activate the chemical reaction that it induces to the formation of clots carries out an inverse task, avoids that these form, favoring bleeding. Both types of enzymes act of simultaneous form. The triggered final picture is transformed in the total consumption of the factors of coagulation and the uncontrolled formation of trombos, taking to the lack of coagulation and a profuse and indetenible hemorrhage.

In order to finalize it is very important to stress that the safest way to save the life to any individual that has been bitten by a poisonous serpent (animal or human) is with the fast administration of the antivenina and with a treatment of suitable support and under strict medical monitoring.

References:

Lancini, A. R. 1979. Serpientes de Venezuela. Armitano Editores. 262 pp.

López-Johnston, J. C. 2000. Consideraciones sobre los venenos de las serpientes, Ms. 78-92.

Rengifo, C y Rodríguez-Acosta, A. 2004. Serpientes, Veneno y Tratamiento Médico en Venezuela. Universidad Central de Venezuela. 80pp.

Rodríguez-Acosta Alexis , Alejandro Mondolfi, Rafael Orihuela, María Aguilar. 1995. ¿Qué hacer frente a un accidente ofídico?. Universidad Central de Venezuela. 46pp.