Inhaled nitric oxide (NO) has emerged as a promising pulmonary vasodilator to treat pulmonary hypertension associated with heart disease and ventilation/perfusion mismatching. However, the pharmacokinetics of inhaled NO still remains obscure and its cardiopulmonary selectivity appears to be increasingly under debate. In the present study measured NO content and levels of cyclic guanosine 3',5'monophosphate (cGMP), a mediator of NO-induced vasodilation, in a variety of organs from rats subjected to NO inhalation. Electron spin resonance spectroscopy associated to a spin trapping technique using N-methyl D-glucamine dithiocarbamate (FeMGD) was used to directly quantify NO levels in the lung, kidney, liver, aorta, and heart from anesthetized Wistar rats subjected to various doses (0, 20, 50, 100, or 200 ppm) and various times (0, 30, 45, or 75 minutes) of inhaled NO. Inhaled NO at a dose of 100 and 200 ppm significantly increased the NO-FeMGD complex in all organs studied. An increase of cGMP was detected in the lung and the aorta after inhaled NO for 45 minutes at the dose of 50 ppm. No changes in NO levels and its metabolites were shown between 30 and 75 minutes of inhaled NO. The results show that inhaled NO at a dose of 100 ppm or more increases NO levels in other organs beside the lung, strongly suggesting that inhaled NO would be more than a pulmonary vasodilator and its selectivity remains to be reconsidered when used for therapeutic purposes.

In ex vivo experiments, 3 hrs after endotoxin injection, vascular responsiveness was sharply decreased. This impaired response was improved in vitro by the inhibition of nitric oxide. The heart response to isoproterenol, nevertheless, was maintained, even though there was an obvious decrease in receptor density and an impaired myocardial accumulation of cAMP. Anti-TNF-alpha antibody partially prevented the alteration of both myocardial pressure response to isoproterenol and biochemical parameters, and was not efficacious in preventing vascular hyporeactivity to vasoconstrictor agents.

Tricyclic antidepressant drugs may affect the cardiovascular system, principally in patients with preexisting cardiac disease. The present study was undertaken to compare the effects of amitriptyline and mianserin with those of tianeptine, an atypical tricyclic antidepressant drug, in rat isolated working heart subjected to a local myocardial ischemia. Coronary, aortic and cardiac flows, and heart rate remained stable during the whole pre-ischemic period in control hearts. Ligation of the left main coronary artery induced a 50% decrease in coronary, aortic and cardiac flow without any change in heart rate. Reperfusion was characterized by the occurrence of ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) and by a marked reduction in cardiodynamic parameters. Amitriptyline (1 and 10 μmol/l) and mianserin (1 and 10 μmol/l) exhibited an anti-arrhythmic activity against reperfusion arrhythmias. Tianeptine (1 and 10 μmol/l) was not able to reduce the incidence of reperfusion arrhythmias. Although tianeptine did not change heart rate, mianserin and amitriptyline induced a bradycardia. Mianserin and amitriptyline improved the cardiac recovery of cardiac function during reperfusion. The cardiodynamic parameters (coronary, aortic and cardiac flows) were not altered by tianeptine during the preischemic period. Furthermore, these parameters were similar to those observed in the control group both during ischemia and reperfusion. The beneficial effects of amitriptyline and mianserin observed in the setting of myocardial reperfusion were not associated with a reduced lipoperoxidation investigated by using an in vitro model in the presence or absence of a free-radical-generating system. The results of the present study indicate that the pronounced antiarrhythmic activities of mianserin and amitriptyline cannot be explained by an antiperoxidative action of these drugs.