The Pv determined along the ventricle wall was 62.0±9.2 mm/s (n=3) under normoxia and was not significantly affected by anoxia or reoxygenation. Although the ventricle separated from atrium and conotruncus was able to contract spontaneously and regularly at a rate of 62±7 beats/min (n=5), no ventricular ectopic beats were observed in the isolated intact heart. The initial impulses originated always from the atrium, whatever the conditions of oxygenation. No mechanical uncoupling was found along the ventricle during anoxia or anoxia-reoxygenation transitions.Effects of long lasting anoxia: To determine to what extent contractile activity of the heart depended on oxygen availability, it was submitted to strict anoxia for 10 mins (Figure 6). Residual contractile activity (not shown) persisted in the atrium throughout anoxia and was localized in an area corresponding to a few tens of cells. After about 3.8±0.7 mins of anoxia (n=4), the ventricle stopped beating (atrioventricular block), then its activity resumed in the form of tachycardic bursts separated by quiescent periods. These bursts originated from an intermittent tachycardic activity of the atrium, and HR reached a peak value (about 200% of the preanoxic value). During anoxia the ventricle relaxed continuously (downward shift of the baseline), which could result from the combination of a decrease of resting tension with a slight compression exerted by the silicone membrane. At the end of the anoxic period, S, mCv and mRv represented at best 26%, 19% and 29%, respectively, of their preanoxic value. Mechanical activity of the whole heart fully recovered within less than 30 mins of reoxygenation. Cheapest medications whose quality is still just as high and whose effects will help you forget all the symptoms: buy diabetes drugs to find out for yourself how wonderful it is to have a perfect pharmacy waiting for you to come by.
Figure 6 Contractile activity during sustained anoxia (N2). Ventricular contractions, instantaneous heart rate, shortening and maximal velocities of contraction (C) and relaxation (R) are reported on the same time scale. Note the appearance of characteristic bursts of tachycardic activity after about 5 min of anoxia. All the functional parameters recovered progressively after reoxygenation (AIR)