Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One of the effects of antiarrhythmic drugs is the reduction of conduction velocity. Cable theory predicts that there is a nonlinear relationship between conduction velocity and upstroke velocity (Vmax) of action potential. By using conventional microelectrode techniques, aprindine-induced reduction of Vmax of action potential and conduction velocity in guinea-pig papillary muscles were measured. Aprindine-produced, use-dependent, and concentration-dependent changes in conduction velocity and the decline of square of conduction velocity was well fit by a single exponential. Time constants for square of conduction velocity were comparable to simultaneously measured time constants for effects of Vmax. At a concentration of 1 to 10 microM aprindine, onset changes between Vmax and conduction velocity had a log-linear relationship in a predicted fashion. Whereas, in the recovery process from aprindine-induced depression, slow recovery time course of conduction velocity was observed. In conclusion, in the presence of aprindine, only onset block of conduction velocity can be analyzed quantitatively in the relationship to observation on Vmax in vitro. These results suggested that in the presence of aprindine, the recovery of internal conductance may be slower than that of Vmax.
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PMID:Effects of aprindine on conduction velocity and Vmax in guinea-pig papillary muscles. 203 7

The depression of Vmax of the action potential in guinea-pig ventricular muscle by aprindine and quanidine was compared. Aprindine caused a more pronounced rate-dependent block (Kd = 10(-6) M at 3.3 Hz) than did quinidine (Kd = 1.6 X 10(-5) M at 3.3 Hz). Aprindine shifted the relationship between Vmax and resting potential to a more negative potential (mean 9.2 mV: 10 microM) than did quinidine (mean 5.7 mV: 10 microM). In addition, aprindine caused a more pronounced resting block (Kd = 1.3 X 10(-5) M) than quinidine (Kd = 8.6 X 10(-5) M). It is concluded that aprindine has a higher affinity for activated and/or inactivated and resting state channels than quinidine, making channels unavailable for conduction upon activation.
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PMID:Comparative study of the block of Vmax by aprindine and quinidine in the guinea-pig heart muscle. 284 19

The effects of antiarrhythmic drugs, aprindine, mexiletine and lidocaine, on rat erythrocytes, isolated rat hepatocytes and DPPC-liposomes were studied at various concentrations. Maximal inhibition of aprindine on the hypotonic hemolysis was observed at a concentration of 2 X 10(-4) M. In isolated rat hepatocytes, aprindine caused an increase in GOT leakage above 4 X 10(-4) M. Mexiletine and lidocaine caused a slight decrease in GOT. Only aprindine caused an increase in LDH leakage above 2 X 10(-4) M. In the relationship between the surface tension and pH conditions (pH 5.7, 7.4 and 8.0), aprindine and mexiletine indicated a depression of surface tension at a dose of 10(-4) M to 10(-3) M under all pH conditions. Lidocaine indicated a depression of surface tension at a dose of 10(-4) M at pH 8.0 only. Aprindine and mexiletine depressed the phase transition temperature (Tc) of DPPC-liposomes. The depression of Tc by aprindine was greater than that by mexiletine. The rank by order of surface activity was the same as that of enzyme leakage from hepatocytes, hemolysis of erythrocytes and depression of Tc in DPPC-liposomes in vitro. These results suggest that differences in membrane damage produced by antiarrhythmic drugs may by related to surface activity, which in turn may determine the extent of adsorption onto cell membranes.
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PMID:[Effects of antiarrhythmic drugs on rat erythrocytes, isolated hepatocytes and dipalmitoyl phosphatidyl choline (DPPC)-liposomes]. 384 Jan 13