Evidence is increasing that vascular tone is highly dependent on the health of the endothelium and on the delicate balancing act between endothelium-derived relaxing and endothelium-derived contracting factors. Moreover, there is also evidence supporting the notion that the same factors which affect vascular tone also regulate, either in an autocrine or paracrine fashion, changes in vascular ar...

The importance of the endothelium in regulating vascular tone and reactivity is well recognized. The endothelium produces a variety of substances including nitric oxide (NO), prostaglandins, endothelin-1, and an unidentified hyperpolarization factor that control vascular tone, thrombus formation, platelet and leukocyte adhesion and aggregation, and cellular proliferation. Alterations in the syn...

The effects of corticosteroids on vascular tone have been recognized since the 1940s. However, despite repeated demonstration of pharmacological effects both in vitro and in vivo, their physiological significance as regulators of tone in health remains to be established. Evidence that abnormal vascular reactivity is important when adrenal steroid production is deranged is more convincing, and p...

Cardiac muscle must maintain a continuous balance between its energy supply and work performed. An important mechanism involved in achievement of this balance is cross talk via chemical signals between cardiac myocytes and the cardiac muscle vascular system. This has been demonstrated by incubating isolated cardiac myocytes in different concentrations of oxygen and then assaying the conditioned...