Jpn. J. Pharmacol. 74 (2), 147-153 (1997)
Beneficial Effects of Dilazep on the Palmitoyl-L-carnitine-Induced Derangements
in Isolated, Perfused Rat Heart: Comparison with Tetrodotoxin
Akiyoshi Hara, Johji Arakawa, Hiroko Hashizume and Yasushi Abiko
Department of Pharmacology, Asahikawa Medical College, Asahikawa 078,
Japan
Abstract: The present study was carried out to determine the
effect of dilazep, having an inhibitory effect on the Na+ channel, on the
mechanical dysfunction and metabolic derangements induced by palmitoyl-L-carnitine
in isolated rat heart and to compare the effect of dilazep with that of
tetrodotoxin, a specific inhibitor of the Na+ channel. Rat hearts were perfused
aerobically at a constant flow according to Langendorff's technique and
paced electrically. Palmitoyl-L-carnitine (5 microM) decreased the left
ventricular developed pressure and increased the left ventricular end diastolic
pressure (i.e., it produced mechanical dysfunction), decreased the tissue
level of adenosine triphosphate and increased the tissue level of adenosine
monophosphate (i.e., it produced metabolic derangements). These mechanical
and metabolic alterations induced by palmitoyl-L-carnitine were attenuated
by either dilazep (1 microM) or tetrodotoxin (3 microM). On the other hand,
neither dilazep nor tetrodotoxin modified the mechanical function and energy
metabolism of the normal (palmitoyl-L-carnitine-untreated) heart. These
results suggest that inhibition of the Na+ channel with dilazep or tetrodotoxin
is responsible, at least in part, for attenuating the palmitoyl-L-carnitine-induced
mechanical dysfunction and metabolic derangements in the heart.
Keywords: Dilazep, Tetrodotoxin, Long-chain acylcarnitine, Na+ channel,
Heart (rat)
Copyright© The Japanese Pharmacological Society 1997
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