How can arterial blood pressure be kept in the normal range during the occlusion/reperfusion procedure?
We measured arterial blood pressure in mice subjected to open-chest surgery.2 The results are summarized in Fig 2. In five mice, one dose of blood (13.3 ml/kg; ~0.4 ml) was given immediately after the thoracotomy in an effort to prevent hypotension. Despite this, mean arterial blood pressure fell to 63.43.7 mmHg after opening the chest (probably due to the loss of negative intrathoracic pressure and to the positive end-expiratory pressure) (Fig. 2). Furthermore, after closing the chest, another drop in blood pressure was noted, to a nadir of 63.09.7 mmHg (Fig. 2). Because these hypotensive episodes could induce ischemic preconditioning, we decided to administer three doses of blood (instead of one): the first was given before opening the chest, the second immediately after opening the chest, and the third after closing the chest. Each dose consisted of 13.3 ml/kg (~0.4 ml). Using this protocol, mean arterial pressure remained at or above 80 mmHg throughout a 1-h period of open-chest st
