Pflügers Archiv

, Volume 433, Issue 6, pp 842–844

Troponin I phosphorylation does not increase the rate of relaxation following laser flash photolysis of diazo-2 in guinea-pig skinned trabeculae

  • Emma C. Johns
  • Sarah J. Simnett
  • I. P. Mulligan
  • C. C. Ashley
SHORT COMMUNICATION

DOI: 10.1007/s004240050353

Cite this article as:
Johns, E., Simnett, S., Mulligan, I. et al. Pflügers Arch (1997) 433: 842. doi:10.1007/s004240050353

Abstract

 In vivo, two effects of β-adrenergic stimulation in cardiac muscle are phosphorylation of troponin I and an increase in relaxation rate. In vitro, cardiac TnI can be phosphorylated by protein kinase A (PKA). We have used the technique of laser flash photolysis of the calcium chelator diazo-2 to investigate the effect of phosphorylation of TnI on the relaxation rate of skinned trabeculae from the guinea-pig at 12°C. The fibres were phosphorylated by PKA, and double exponential curve fits of the average relaxation transients showed no significant difference between the rate constants of the phosphorylated and control cases. We conclude that TnI phosphorylation has no effect on the rate of relaxation in skinned trabeculae from the guinea-pig following diazo-2 photolysis.

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Emma C. Johns
    • 1
  • Sarah J. Simnett
    • 1
  • I. P. Mulligan
    • 2
  • C. C. Ashley
    • 1
  1. 1.University Laboratory of Physiology, Parks Road, Oxford, OX1 3PT, UKGB
  2. 2.Department of Cardiology, John Radcliffe Hospital, Oxford, OX3 9DU, UKGB