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The effect of naphthylmethyl isoquinoline on amplitude of contraction and automaticity of guinea pig atria were investigated. The compound was found to markedly inhibit the force of contraction and automaticity in a concentration-dependent way. Propranolol competitively antagonized the effect of isoproterenol with pA2 of 7.5. Naphthylmethyl isoquinoline and verapamil antagonized isoproterenol, but in a noncompetitive manner with the pD2' of 5.4 and 5.8, respectively. The effect of the compound on action potential and contractile force of guinea pig papillary muscles were also studied. It was shown to produce negative inotropic effects and shorten the fast action potential duration, but the maximal upstroke (Vmzx) and amplitude of action potential were not affected. Thus, an excitation-contraction uncoupling was observed. It also depressed the amplitude. Vmax and duration of Ca2(+)-mediated slow action potential induced by high K+. Elevation of the CaCl2 concentration from 2 to 5 mmol/L reversed its inhibition partially. These results indicate that naphthylmethyl isoquinoline has a blocking effect on calcium channels.
H T Yang, and
Y L Yang
November 1989,
Zhongguo yao li xue bao = Acta pharmacologica Sinica,
H T Yang, and
Y L Yang
December 1972,
European journal of pharmacology,
H T Yang, and
Y L Yang
January 1974,
Naunyn-Schmiedeberg's archives of pharmacology,
H T Yang, and
Y L Yang
May 1987,
Zhongguo yao li xue bao = Acta pharmacologica Sinica,
H T Yang, and
Y L Yang
January 1989,
Archivos del Instituto de Cardiologia de Mexico,
H T Yang, and
Y L Yang
December 1988,
Endocrinology,
H T Yang, and
Y L Yang
September 1969,
The Journal of pharmacy and pharmacology,
H T Yang, and
Y L Yang
April 1972,
British journal of pharmacology,
H T Yang, and
Y L Yang
May 1979,
Archives internationales de pharmacodynamie et de therapie,
H T Yang, and
Y L Yang
January 1978,
Roczniki Akademii Medycznej im. Juliana Marchlewskiego w Bialymstoku,
