Additionally, with programmed stimulation, the AV (AV-ERP), atrial (A-ERP) and ventricular (V-ERP) ERPs and the rate-dependent ERPs of the AV node, and of the atrial and ventricular myocardium were estimated at concentrations of 1, 3 and 10 |J.M of either drug.
Stimulation protocol – ERP: Under control conditions and 15 mins after the addition of each concentration (1,3 and 10 |J.M) of either drug, the ERP and the rate-dependent ERP of AV conduction, and the atrial and ventricular myocardium were determined. Stimuli were delivered through Teflon-coated silver wire electrodes placed on the epicardial surface of the left auricle for the measurement of atrial and AV nodal refractoriness. For evaluation of the ERP of the ventricle, the stimulation electrodes were placed on the apex of the right ventricle. The stimulation threshold was evaluated at the beginning of the pacing protocol. A programable stimulator with separate constant current output delivered rectangular stimuli of 2 ms duration at an intensity of twice the late diastolic threshold. The ERPs were evaluated with a conditioning train of 10 basic stimuli (S1). The S1-S1 interval was 240 ms and the S1-S2 interval was shortened in steps of 1 ms. After each step the heart was allowed to recover from pacing for 1 s. The longest S1-S2 interval for a stimulus that failed to induce an atrial or ventricular response was defined as A-ERP or V-ERP, respectively. The longest S1-S2 interval for a stimulus that failed to conduct through the AV node and to produce a His bundle response was defined as the AV-ERP. You can be sure your pharmacy offers Xopenex Price click here delivering fast internationally.