title: An experimental model of giant negative T wave associated with QT prolongation produced by combined effect of calcium and isoproterenol.
abstract: Changes of the surface ECG and monophasic action potential induced by isoproterenol injection were investigated under normo- and hypercalcemic conditions in dogs. (1) Biphasic time course of T wave changes, initially inverted and subsequently uprightly tall, was observed after intravenous injection of isoproterenol in doses of more than 2 microgram. (2) Initial prolongation and subsequent shortening of the phase 2 of action potential were observed on the ventricular surface in accordance with the biphasic time course of the T wave changes on the surface ECG after isoproterenol injection. (3) Giant T wave inversion associated with QT prolongation was obtained by isoproterenol injection under hypercalcemia. (4) Marked prolongation of total duration as well as phase 2 of action potential was observed in accordance with the giant negative T wave on the surface ECG. Although the mechanism of this experimental model of giant negative T wave is not clear, this model could have important suggestions on the unknown mechanism of giant negative T wave observed in various clinical status.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D004285:Dogs; D004562:Electrocardiography; D006934:Hypercalcemia / Q000503:physiopathology; D007545:Isoproterenol / Q000494:pharmacology*
chemical_list: D007545:Isoproterenol; D002118:Calcium