The Homing Tendency of Shad

Abstract

within a few minutes, whereas ryanodine alone ordinarily causes rigor in 3-4 hrs. Ryanodine-ATP injections caused a 9-fold increase in oxygen consumption in the roach, and in one case, where the ATP had been warmed to 450 C and then cooled to room temperature before mixing with the ryanodine, the oxygen consumption was increased to 18 times normal following injection. In the intact roach the ryanodine-ATP effect was reversible in the concentrations used. In the intact frog and the rectus preparations the rigor produced was irreversible. These results strengthen our belief that ryanodine acts specifically on the contractile process in striated muscle and indicate that the mode of action is probably one of interference with the phosphagen-ATP-ADP-actomyosin cycle during contraction.