Fluorescence polarization: a novel indicator of cardiomyocyte contraction.
The changes measured in intracellular fluorescein fluorescence polarization (IFFP) are used as a new tool for tracing cytoplasmic effects during contractile cycles of cardiac myocytes (1-2-day-old rat hearts), in addition to the established Ca(2+) monitoring and/or videometric methods of tracking cell-shortening. This novel method was found to be non-intrusive to the contraction cycles. The decay of the transient IFFP signal (from 0.220+/-0.01 to 0.170+/-0.013) seems to be closely related to the extended phase of contractile activation. This fact was further supported when Ca(2+) exchanger inhibitor was introduced and significantly decreased (90%) the rate of beats of contraction and IFFP, but not the Ca(2+) beat rate changes. This result suggests that the IFFP indicator is probably associated with the physiological activation, rather than with Ca(2+) alterations. The IFFP measure monitors the average of effective changes in the micro-viscosity of the cytoplasm protein matrix, associated with cellular activation.
Fixler
Dror
D
The Biophysical Interdisciplinary Schottenstein Center for the Research and the Technology of the Cellome, Physics Department, Bar-Ilan University, Ramat-Gan 52900, Israel. fixeled@mail.biu.ac.il
Tirosh
Reuven
R
Zinman
Tova
T
Shainberg
Asher
A
Deutsch
Motti
M
D000818:Animals; D020013:Calcium Signaling; D002478:Cells, Cultured; D019793:Fluorescein; D005454:Fluorescence Polarization / Q000379:methods*; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D051381:Rats
D019793:Fluorescein