Session 10 : Pharmacologie moléculaire et cellulaire, signalisation, transduction

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Session 10 : Pharmacologie moléculaire et cellulaire, signalisation, transduction

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IMPACT OF G-PROTEINS ON CALCIUM SENSITIVITY OF TENSION IN THE RAT TAIL ARTERY

E. Spitzbarth, M.A. Petitcolin1, E.J. Tschirhart1 and C. Capdeville-Atkinson.

Laboratoire de Pharmacologie Cardiovasculaire, UHP-Nancy 1, 54000 Nancy, France, and 1 Centre de Recherche Public Santé,
L-1150 Luxembourg

In vascular smooth muscle cells, KCl-induced vasoconstriction shows weak calcium ([Ca2+]i)-sensitivity whereas agonist-induced vasoconstriction shows high [Ca2+]i-sensitivity, suggesting an amplification of pharmacomechanical but not of electromechanical coupling. The aim of this study was to investigate whether PTX-sensitive G-proteins are involved in the [Ca2+]i-sensitivity of tension. De-endothelialised, perfused rat tail arteries were loaded with Fura-2/AM (5 µM, 90 min) and PTX (0, 30, 100, 300 or 1000 ng.ml-1). They were stimulated with either high KC1 (80 mM, 2 min) or noradrenaline (3 µM, 2 min. NA). KC1- or NA-evoked increases in perfusion pressure (

D P, mmHg) and [Ca2+]i mobilisation (D [Ca2+]i, a.u.) were measured. Values are means± S.E.M, significant differences between means (* P