Abstract
The aim was to investigate whether the positive inotrope DPI 201-106 prolongs ventricular monophasic action potential duration and refractoriness in vivo without affecting conduction, thus possessing class III antiarrhythmic characteristics in vivo. Electrophysiological and haemodynamic effects of DPI 201-106 (0.5, 1.0, and 2.0 mg.kg-1 intravenously) were studied at spontaneous heart rate and at three different paced cycle lengths (353, 300, and 261 ms). The following were recorded: monophasic action potentials from right ventricular endocardium; intracardiac conduction times by His bundle electrocardiography; refractoriness by programmed electrical stimulation; and left ventricular (LV) pressures. Seven mongrel dogs of either sex, weighing 14-24 kg, were studied under sodium pentobarbitone anaesthesia. DPI 201-106 prolonged ventricular monophasic action potential duration and refractoriness dose dependently and most effectively at long cycle lengths, with no effect on intracardiac conduction times. DPI 201-106 increased LV dP/dtmax, while LV systolic and end diastolic pressures were unchanged both during spontaneous and paced heart rate. DPI 201-106 decreased spontaneous heart rate. Prolonged monophasic action potential duration and increased refractoriness, with no effect on conduction, indicate class III antiarrhythmic action of DPI 201-106 in vivo.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
