@article{oai:nagoya.repo.nii.ac.jp:00016500, author = {MAEDA, KIYOSHI and ITO, KEIZO and SEKIYA, ATSUSHI and KANDA, ZENGO}, issue = {1}, journal = {Nagoya Journal of Medical Science}, month = {Jun}, note = {Effects of ouabain and catecholamines_ and their modifications_ by propranolol were investigated on the functional refractory period (FRP), contractile force and heart rate in isolated atria of guinea-pigs and rats. Catecholamines produced a transient decrease in the FRP of guinea-pig atria, while ouabain caused a continual increase after a latent period of 5 to 10 minutes. The FRP in rat atria was_ increased by either ouabain or catecholamines. Pretreament with propranolol, which by itself produced a moderate increase in the FRP, completely blocked the effects of catecholamines, but did not prevent those of ouabain in both atria. It seems from these data on the FRP changes_ that no evidence was_ obtained for a ouabain-catecholamine relationship. However, from the observation on the spontaneously beating atria that the toxic effects of ouabain on contractility and rhythmicity were markedly reduced by propranolol it would be suggested that catecholamines might be related to the action of ouabain in its toxic stage.}, pages = {121--128}, title = {Effects of Ouabain and Catecholamines on the Refractory Periods and Contractions of Isolated Atria}, volume = {30}, year = {1967} }