Infarct size-limiting properties of Ro 40-5967, a novel nondihydropyridine calcium channel, in anesthetized rats: comparison with verapamil.

We assessed the hemodynamic and infarct size (IS)-limiting effects of the new calcium antagonist Ro 40-5967 in a rat model of ischemia/reperfusion and compared the effects of Ro 40-5967 with those of verapamil. Open-chest rats underwent 20-min coronary occlusion followed by 2-h reperfusion. We determined area at risk (AAR) and IS at the end of reperfusion by India ink injection and triphenyltetrazolium chloride (TTC) staining, using computerized analysis of enlarged sections after color video acquisition.

Nitric oxide is responsible for flow-dependent dilatation of human peripheral conduit arteries in vivo.

Background: Experimental evidence suggests that flow-dependent dilatation of conduit arteries is mediated by nitric oxide (NO) and/or prostacyclin. The present study was designed to assess whether NO or prostacyclin also contributes to flow-dependent dilatation of conduit arteries in humans.

Methods And Results: Radial artery internal diameter (ID) was measured continuously in 16 healthy volunteers (age, 24 +/- 1 years) with a transcutaneous A-mode echo-tracking system coupled to a Doppler device for the measurement of radial blood flow.

Influence of sympathetic tone on mechanical properties of muscular arteries in humans.

Although smooth muscle tone is a key determinant of mechanical properties of arteries in animal experiments, it has not yet been studied in humans because of technical limitations. To assess the influence of tone on arterial properties in humans and to emphasize the interest of calculation at specific stress, we used echo tracking and photoplethysmographic measurement of arterial pressure to study radial arterial mechanics during a cold pressor test (CPT) in 12 healthy volunteers (28 +/- 2 yr). During CPT, mean arterial pressure rose from 83 +/- 3 to 106 +/- 5 mmHg (P < 0.

In vivo evidence of an endothelin-induced vasopressor tone after inhibition of nitric oxide synthesis in rats.

Background: Continuous production of nitric oxide (NO) from endothelial cells permanently inhibits the synthesis and the vasoconstrictor effects of endothelin. Thus, inhibition of NO synthesis might unmask a vasopressor response to endothelin. To assess whether endothelin contributes to the pressor response induced by inhibition of NO synthesis, we tested whether bosentan, a nonpeptide antagonist of ETA and ETB endothelin receptors, affected the hypertensive response induced by the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME).

Role of endogenous endothelin in myocardial and coronary endothelial injury after ischaemia and reperfusion in rats: studies with bosentan, a mixed ETA-ETB antagonist.

1. Previous studies suggested that endothelin-1 (ET-1) may play a role in myocardial ischaemia and reperfusion. This study was designed to test the effect of a new nonpeptide antagonist of endothelin ETA and ETB receptors, bosentan, on myocardial infarct size, ventricular arrhythmias, and coronary endothelial dysfunction after ischaemia and reperfusion.