R. Rodenkirchen

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1. The effects of nifedipine (3×10−11–3×10−6 M) on contractile activity and transmembrane action potential (AP) were studied in isotonically contracting cat papillary muscles and in isolated SA-nodes. 2. Nifedipine (3×10−8–3×10−6 M) reduces the amplitudes of contraction. The effect is nearly independent of stimulation rate such that at 6/min the ED50(More)
1. The effects on contractile activity of 2 series of nifedipine-derivatives were investigated in isolated, isotonically contracting cat papillary muscles. 2. For structure-activity studies the lipophilicity of all compounds was determined by means of reversed phase thin-layer chromatography. 3. Neither the ortho-NO2 group in a series of arylderivatives nor(More)
The influence of ring substitution on the negative-inotropic action of the Ca-antagonist verapamil (Isoptin) by means of qualitative and quantitative analyses of the structure-activity relationships has been investigated. The relative contribution of the two aromatic rings to the negative-inotropic potency of verapamil was tested. a) Ring substituents(More)
pK-Values of Ca-antagonists and related cardiodepressive drugs have been measured by means of potentiometric microtitration. The presumable active species for all compounds investigated is the protonated molecule except nifedipine. This drug must exert its action via the uncharged form. From these results it could be concluded that protonization of(More)
1. In isotonically shortening cat papillary muscle 3-(2-di-ethylaminoethyl)-4-methyl-7-(carbethoxy-methoxy)-2-oxo-1,2-chromene-hydrochloride (carbocromen; Intensain¿) (1-30 mug/ml) slightly increases contraction amplitude. 2. At low stimulation rates (6-12/min) the positive inotropic effect is more pronounced. 3. The maximal velocity of depolarization of(More)
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