Pressure sensitivity of active tension in glycerinated rabbit psoas muscle fibres: effects of ADP and phosphate.
The effect of changes in hydrostatic pressure (up to 10 MPa) on the maximally calcium-activated tension in glycerinated rabbit psoas fibres has been examined. The steady active tension was depressed by 0.8% per MPa pressure rise. This pressure sensitivity was enhanced by the pressure of millimolar phosphate and depressed by millimolar ADP. These results support the conclusions that increased pressure is perturbing a crossbridge event. The results are discussed in terms of a three state crossbridge model and are shown to be compatible with a pressure effect on the transition from an attached crossbridge state to a tension bearing state. This is compatible with the effects of pressure on the isolated proteins in solution.
Department of Biochemistry, University of Bristol, School of Medical Sciences, U.K.
N S
NS
Fortune
M A
MA
Geeves
K W
KW
Ranatunga
D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000818:Animals; D005990:Glycerol; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000502:physiology*; D010710:Phosphates / Q000494:pharmacology*; D011312:Pressure; D011817:Rabbits
D010710:Phosphates; D000244:Adenosine Diphosphate; D005990:Glycerol