Hearts were first perfused in sinus rhythm with normal Tyrode’s solution for comparison. As shown in Figure 1, heart rate decreased continuously from 195±4 beats/min to 161±6 beats/min after 170 mins. This small decline was statistically significant from 90 mins of perfusion onwards. QTc started at 0.31±0.01 s and change was not statistically significant until 160 mins of perfusion. Only in the last 10 mins of the experiment was there a very small but statistically significant increase in QTc of 0.02 s. Left ventricular peak pressure decreased continuously from 51±3 to 34±2 mmHg (P<0.001) over the 170 mins of perfusion.
Hearts in atrioventricular (AV) rhythm, when perfused with Tyrode’s solution containing drug solvent, have shown qualitatively the same changes over time. Notably, the initial AV rate was 126±6 beats/min. Visit the best pharmacy giving you proventil inhaler dosage and taking the best care of you.
Figure 1 Langendorff-perfused intact guinea-pig hearts. Sinus heart rate (HR), corrected QT (QTc) time in the endocardial electrocardiogram and left ventricular isometric peak pressure (LVP) are presented as measured during 170 mins of perfusion with normal Tyrode’s solution. Values are mean ± SEM, n=6. Stastistically significant changes as calculated with Student’s paired t test were obtained between P<0.05 and P<0.001 for HR at 90 mins, for QTc at 150 mins and for LVP at 60 mins