myotoxin-a and Hemorrhage

A mixture of antimyotoxin a serum and polyvalent (Crotalidae) antivenom was injected i.v. in mice either 5 min before or 5 min, 30 min, 1 hr or 3 hr after i.m. injection of venom. Neutralization of the local myotoxicity of a sublethal dose (1.5 micrograms/g) of C. v. viridis venom occurred if the antisera were injected 5 min before or 5 or 30 min after venom, but not if injected 1 or 3 hr after the venom. Hemorrhage was neutralized when the mixture was injected either 5 min before or 5 min after injection of venom, but not when injected 30 min after injection of venom. Previous results showed that the mixture of antisera neutralized the same amount of venom (1.5 micrograms/g) when mixed with the venom prior to injection. Thus it is not possible with these two antisera to neutralize myonecrosis if the time interval between injections is greater than 30 min.

Topics: Animals; Antivenins; Crotalid Venoms; Female; Hemorrhage; Mice; Necrosis; Neutralization Tests; Time Factors

Mixtures containing polyvalent (Crotalidae) antivenin and antimyotoxin a serum were tested for their ability to neutralize the myotoxic, hemorrhagic and lethal activities of crude C. v. viridis venom when mixed with the venom prior to injection into white mice. A light microscopic method was used to measure the local myotoxic activity of the venom, i.e. myonecrosis index. The results show that the neutralizing ability of a 1:1 mixture of antisera for myonecrosis was 16 times that of antimyotoxin a serum alone and 63 times that of antivenin alone. There was no difference in neutralizing ability of the three ratios (2:1, 1:1, 1:2) of antivenin: antimyotoxin serum tested. Hemorrhage was measured by a new method in which the amount of hemoglobin in a muscle extract was measured after i.m. injection of test solution. The results show that the ability of a 1:1 mixture to neutralize hemorrhage was comparable to that of antivenin alone. There was no difference in hemorrhage neutralizing ability of the three ratios tested. In its ability to neutralize lethality, the 1:1 mixture was again comparable to antivenin. However, when the three different ratios of antisera were tested for neutralization of lethality the 2:1 and 1:1 ratios were as effective as antivenin alone, whereas the 1:2 ratio (antivenin: antimyotoxin serum) was less effective than antivenin alone. Thus the addition of antimyotoxin a serum to antivenin in equal proportions greatly improves the neutralization of the myotoxic activity of C. v. viridis venom and does not decrease the ability of antivenin to neutralize hemorrhage and lethality.

Topics: Animals; Antivenins; Crotalid Venoms; Female; Hemorrhage; Immune Sera; Lethal Dose 50; Mice; Muscular Diseases; Necrosis

A previously unknown polypeptide myotoxin, designated myotoxin a, was isolated for the first time from prairie rattlesnake (Crotalus viridis viridis) venom. Electrophoretic homogeneity of myotoxin a was shown in beta-alanine disc gel polyacrylamide gel electrophoresis and in isoelectric focusing gel electrophoresis. Molecular weight and isoelectric point estimates of 4100 and 9.6 were obtained by gel filtration and isoelectric focusing gel electrophoresis, respectively. Amino acid composition showed a total of 39 amino acid residues, with 10 lysine residues and two disulfide bridges. When the two disulfide brides were reduced and alkylated, the myotoxic activity was abolished, indicating that the disulfide bridges of myotoxin a are essential for its biological activity. The loss of the biological activity is probably due to a marked change in secondary structure. The circular dichroic spectrum indicates that the chemically modified, inactive myotoxin exhibits typical random-coil conformation.

Topics: Amino Acids; Animals; Chemical Phenomena; Chemistry; Circular Dichroism; Crotalid Venoms; Disulfides; Dogs; Electrophoresis, Disc; Hemolysis; Hemorrhage; In Vitro Techniques; Isoelectric Focusing; Isoelectric Point; Mice; Molecular Weight; Muscular Diseases; Oxidation-Reduction; Snake Venoms; Structure-Activity Relationship