Alleviation of contractile dysfunction in isolated globally
ischemic and reperfused guinea-pig hearts by slowly inactivating na+
current blockers.
Grand, B. Le, B. Vie, J. M. Talmant, E. Coraboeuf, G. W. John.
Centre de Recherche Pierre FABRE, Division of Cardiovascular
Diseases, 17 Avenue Jean Moulin, 81106 CASTRES CEDEX, FRANCE
APStracts 2:0115H, 1995.
We hypothesized that the slowly inactivating component of Na+ current,
which is an integral part of the Na+ window current, is a major
pathway for Na+ loading during myocardial ischemia. The putative
protective effects of tetrodotoxin (TTX) and R 56865, at
concentrations which selectively blocked the Na+ window current, as
assessed by action potential plateau shortening without affecting
maximum upstroke velocity (Vmax), were examined in isolated,
Langendorff-perfused guinea-pig hearts subjected to 50 min
normothermic global ischemia and 60 min reperfusion. The
concentration ranges in which these drugs selectively shortened the
plateau duration were determined in a separate series of experiments
on isolated guinea-pig papillary muscles, in which action potentials
were measured by conventional intracellular recording techniques.
Received 27 December 1994; accepted in final form 13 March 1995.
APS Manuscript Number H1134-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.