Posts Tagged ‘Nitric oxide

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 […]

RESULTS   Because changes in the hemodynamic variables produced by myocardial ischemia and by NONLA were measured in the same animal and changes in coronary flow were measured in the same ventricular transmural layers in each dog, the results were analyzed by Student’s paired t test. The null hypothesis was discarded with P<0.05. Results are […]

The effect of NONLA was considered adequate when the response of circumflex coronary flow to the intracoronary administration of acetylcholine (5.5 nmol/kg diluted in 0.5 mL saline) was reduced by at least 80% . Fifteen minutes later ischemia was again induced by decreasing the peripheral coronary pressure, and regional flow was measured with the microspheres […]

Experimental design: After the surgical procedure a period of 15 mins was allowed for hemodynamic variables to stabilize. The following protocol was followed in each of the 14 dogs. Ischemia was induced by decreasing the peripheral coronary pressure with the occluder from its control value to a pressure of about 25 mmHg. After 1 min […]