title: The stiffness of the flagella of impaled bull sperm.
abstract: The elastic rigidity (stiffness) of impaled motionless bull sperm flagella has been determined by a manipulatory technique which permitted direct analytical treatment of the experimental system. The effects of external ATP and ADP were measured. It was found that ATP acts as a plasticizing agent, while ADP does not. The stiffness measured for flagella in a medium without ATP was 15 times greater than the value measured with 10 mM ATP present. The rigor-like stiffness measured with no ATP present is reversible with ATP and seems to be correlated to a transition in the state of the contractile system.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D003486:Cyanides / Q000494:pharmacology; D005407:Flagella / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008433:Mathematics; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*
chemical_list: D003486:Cyanides; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate