Archive for the ‘Cardiology’ Category

Furthermore, although the release of nitric oxide through a signal from the ischemic myocardium may also explain part of the vasodilation observed during reactive hyperemia , it is well known that the increase in flow during reactive hyperemia is in excess of the oxygen debt established during the occlusion, as revealed by the persistence of […]

The changes in flow in the present experiments represent changes at the time of ischemia occurrence by a partial occlusion of a coronary artery, while those during reactive hyperemia correspond to changes at the time of repayment of flow after ischemia produced by the total occlusion of a coronary artery. Therefore, transmural flow distribution during […]

Our results show that the inhibition of nitric oxide synthesis produces a proportionally larger decrease of flow in the inner than in the outer layer of the ischemic left ventricular wall with a reduction of the I:O flow ratio below that observed by the effect of the sole ischemia. This result agrees with that of […]

Other substances such as adenosine, a metabolite that is produced during myocardial ischemia , has been proposed as mediator for the release of nitric oxide in the endothelium; however, in isolated canine coronary microvessels, Jones et al showed that inhibition of nitric oxide synthesis does not affect the dilation of isolated arterioles by adenosine, suggesting […]

Changes in transmural flow distribution effected of NONLA cannot be ascribed to alterations in the mechanical forces across the wall because no significant changes were observed in left ventricular pressure and heart rate, and the small increase in left ventricular end-diastolic pressure during ischemia was similar before and after administration of NONLA. Because microsphere measurements […]

DISCUSSION Our results show that nitric oxide is an important mediator in the regulation of coronary bloodflow mainly in the ischemic myocardium. In fact, inhibition of nitric oxide with NONLA decreased flow through all layers of the left ventricular wall in the ischemic region, but only in the subepicardial layer in the nonischemic region (Figures […]

Figure 1A shows the effect of NONLA on the distribution of flow across four layers of the left ventricular free wall, from the inner to the outer, in the nonischemic region in 14 experiments in the 14 dogs. Before inhibition of nitric oxide synthesis with NONLA, flow was similar in the four layers across the […]