The underlying pathology of most cardiovascular diseases (CVDs) such as coronary artery disease, high blood pressure, and stroke involves decreased cardiovascular contractility and anatomic alterations in cardiovascular structures. Nitric oxide (NO) regulates vascular tone and contractile function of myocardium and maintains blood vessel homeostasis. Interestingly, the effect of NO is like a double-edged sword in the body. Insufficient NO causes hypertension and atherosclerosis, while an overproduction of NO may foster inflammation and cause heart infarction and shock. In addition, growing evidences have shown that oxidative stress plays pivotal roles in the initiation and progression of CVDs. This chapter will discuss in detail the roles NO plays in the cardiovascular system under both physiological and pathological conditions. We will focus on: (1) the molecular mechanism of cardiovascular contraction, (2) NO/Ca 2+-induced muscle relaxation, (3) NO-related structural change in blood vessels, and (4) redox balance in the cardiovascular system. The relationships between these molecular mechanisms and the characteristics of CVDs will be highlighted.
Diabetic foot ulcers (DFU) are a major health problem associated with diabetes mellitus. Impaired nitric oxide (NO) production has been shown to be a major contributor to the dysregulation of healing in DFU. The level of impairment is not known primarily due to challenges with measuring NO. Herein, we report the actual level of NO produced by human dermal fibroblasts cultured under normal and high glucose conditions. Fibroblasts produce the extracellular matrix, which facilitate the migration of keratinocytes to close wounds. The results show that NO production was significantly higher in normal glucose compared to high glucose conditions. The real-time NO detected was compared to the nitrite present in the culture media and there was a direct correlation between real-time NO and nitrite in normal glucose conditions. However, real-time NO detection and nitrite measurement did not correlate under high glucose conditions. The inducible nitric oxide synthase (iNOS) enzyme responsible for NO production was upregulated in normal and high glucose conditions and the proliferation rate of fibroblasts was not statistically different in all the treatment groups. Relying only on nitrite to assess NO production is not an accurate determinant of the NO present in the wound bed in pathological states such as diabetes mellitus.
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