A pharmacological evaluation of electrical events in the myocardium.
The pharmacologist is interested in both the therapeutic effect of the drug and its mode of action. This latter is mainly studied in the isolated heart in vitro. However, in vitro experiments are not satisfactory to predict antiarrhythmic activity in vivo because: they are mostly performed in preparations made from the normal myocardium; in vitro the autonomic and hormonal effects are absent; some drugs such as nitroglycerine or strophanthin do not produce antiarrhythmic electrophysiological changes in vitro but under appropriate conditions may have a clear-cut antiarrhythmic action in vivo; and arrhythmias mostly arise from the interaction of changes in several fundamental electrophysiological parameters which could be best studied in vivo. These facts are demonstrated by the example of the pathomechanism and pharmacotherapy of early postinfarction arrhythmias. In spite of these shortcomings, there is, however, some promising development in this field. Progress is being made in the in vivo recording of electric events in the heart (multiple KCl suction electrodes, in vivo recording of Purkinje activity). Prolonged drug treatment can evoke electrophysiological changes in vitro characteristic of the action of the drug in vivo. In the donor-perfused isolated heart preparation, the drug administered to the donor animal will evoke responses in concentrations producing the in vivo effect, and the possibility of drug metabolism and binding to plasma proteins is also present.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002302:Cardiac Output / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D004562:Electrocardiography; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects; D008012:Lidocaine / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000201:enzymology; D010869:Pindolol / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D011690:Purkinje Fibers / Q000187:drug effects; D011817:Rabbits; D012849:Sinoatrial Node / Q000187:drug effects; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D007473:Ion Channels; D008012:Lidocaine; D010869:Pindolol; D014700:Verapamil; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D002118:Calcium