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Brevetoxin-B (GbTX-B), a cyclic polyether purified from the marine dinoflagellate Gymnodinium breve, produced positive inotropic and arrhythmogenic effects on isolated rat and guinea pig cardiac preparations at concentrations between 1.25 X 10(-8) and 1.87 X 10(-7) M. The toxin (10(-7) M) transiently increased left ventricular +dP/dt, hydraulic work, and oxygen consumption of paced working rat hearts, then reduced these variables during continuous exposure. Brevetoxin-B exerted a much smaller positive inotropic effect on working guinea pig hearts, but produced a marked and sustained inotropic effect on guinea pig left atria. The toxin also produced arrhythmias in rat and guinea pig hearts, characterized by ventricular tachycardia and A-V blockade. Sympatholytic procedures (beta blockade or reserpine pretreatment) partially blocked the positive inotropic effects, and eliminated the ventricular tachycardia, but not the A-V blockade. Tetrodotoxin markedly inhibited the positive inotropic effect of GbTX-B. Brevetoxin-B did not inhibit guinea pig cardiac Na,K-ATPase activities. The results show that GbTX-B is a potent cardiotoxin and suggest that GbTX-B exerts positive inotropic and arrhythmogenic effects by increasing sarcolemmal sodium permeability, and by releasing catecholamines from sympathetic nerve endings.
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
January 1984,
Basic research in cardiology,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
February 1982,
Archives internationales de pharmacodynamie et de therapie,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
March 1991,
Zhongguo yao li xue bao = Acta pharmacologica Sinica,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
December 1977,
Naunyn-Schmiedeberg's archives of pharmacology,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
June 1989,
European journal of pharmacology,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
January 1990,
Life sciences,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
March 1990,
Critical care medicine,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
September 1987,
British journal of pharmacology,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
May 1988,
European journal of pharmacology,
R L Rodgers, and
H N Chou, and
K Temma, and
T Akera, and
Y Shimizu
January 1993,
Archives internationales de pharmacodynamie et de therapie,
