Vascular system nitric oxide affecting

When given rapidly, protamine causes hypotension due to a decrease in vascular resistance, possibly linked to the release of nitric oxide from endothelium. Flypotension can be minimised by slow administration over 10-15 minutes. Protamine does not affect myocardial contractility. In some patients, systemic hypotension occurs in conjunction with pulmonary hypertension and, in severe cases, right ventricular failure. The mechanism is activation of the complement pathways by the heparin-protamine complex leading to release of thromboxane A2, which mediates pulmonary vasoconstriction. Unlike in anaphylaxis, plasma histamine concentrations are not increased. When this syndrome develops protamine administration should be stopped, and some have recommended giving heparin in an attempt to reduce the size of the heparin-protamine complex. 

Although the overall yield is small, 4-nitrosophenol is a significant product from addition of ONOO" alone (Fig. 3). ONOO"-mediated formation of nitroso adducts in biological systems, particularly nitrosothiols, likely accounts for the ability of ONOO" to produce nitric oxide-like effects such as vascular relaxation (Wu et al., 1994 Liu et ah, 1994). The yield of 4-nitrosophenol from ONOO" is not significantly affected by lowering the pH to 6.0 but does increase at pH 8.0 (Fig. 3). At pH 7.4 the yield of nitrosophenol increased severalfold when ONOO" and nitric oxide were added simultaneously. The yield of nitrosophenol from ONOO plus nitric oxide was essentially no different from that of nitric oxide alone at pH 6.0 or pH 8.0. 

The metabolic countermeasures are characterized by the regulatory role of ascorbate for metabolic systems determining the clinical risk profile for CVD. The common aim of these metabolic regulations is to decrease the vascular permeability in ascorbate deficiency. Low ascorbate concentrations therefore induce vasoconstriction and hemostasis and affect vascular wall metabolism in favor of atherosclerogenesis. Towards this end ascorbate interacts with lipoproteins, coagulation factors, prostaglandins, nitric oxide, and second messenger systems such as cyclic monophosphates (for review see 1, 3-5). It... 

---