Effects of Mojave toxin on rat skeletal muscle sarcoplasmic reticulum

Effects of the lethal fraction (MD-9) from the venom of the Mojave rattlesnake, Crotalus scutulatus , on sarcoplasmic reticulum were investigated. The calcium sequestering activity of the vesicles was reduced by the lethal fraction and subsequent release of calcium was enhanced. These effects were observed to be dependent upon MD-9 concentration and the length of preincubation time with the vesicles. An enhanced ATPase activity that was affected by concentration and MD-9 preincubation time was also observed. Both calcium uptake and ATPase activity effects may be due to a phospholipase activity associated with the fraction.