Kevin S. Rud

Plasma Nitric Oxide Before and After Smoking Cessation with Nicotine Nasal Spray

Nicotine may affect cardiovascular function through release of neurotransmitters from autonomic nerves or release of vasoactive substances from the vascular endothelium. Nitric oxide is a neurotransmitter and endothelium‐derived factor that reduces tone of vascular smooth muscle. Experiments were designed to determine whether or not use of nicotine nasal spray for smoking cessation affects plasma levels of nitric oxide. Forty smokers self‐administered nicotine by nasal spray (one 0.5 mg spray to each nostril). Blood samples were taken before the use of the nasal spray and at treatment day 7 for the measurement of cotinine by high pressure liquid chromatography and nitric oxide (NOx) by chemiluminescence. Age‐comparable controls were never‐smokers nonnicotine users recruited from laboratory personnel. Mean plasma concentrations of NOx from smokers before treatment were significantly greater compared with nonsmokers (23 ± 10, n = 40 and 15 ± 6, n = 13 nmoles/mL [mean ± SD], respectively, P < 0.01). Plasma NOx in smokers was not significantly correlated with the average daily number of cigarettes smoked (r2 = 0.02, P > 0.05) but was positively and linearly correlated with plasma cotinine (r2 = 0.13, P < 0.02). In 32 self‐reported abstinent smokers (confirmed by expired carbon monoxide < 9 ppm) using nicotine nasal spray, cotinine decreased by 64% from pretreatment levels of 284 ± 103 to posttreatment levels of 90 ± 58 ng/mL. Plasma NOx was unchanged and went from 23.0 ± 10.1 at pretreatment to 21 ± 12 nmoles/mL with nicotine treatment. These results suggest that nicotine‐use, independent of cigarette smoking, affects plasma NOx.

Mechanism of raloxifene-induced relaxation in femoral veins depends on ovarian hormonal status

Experiments were designed to study effects of raloxifene, a selective estrogen receptor modulator, on venous endothelium and smooth muscle. Rings of femoral veins with and without endothelium from adult gonadally intact, and ovariectomized female pigs were suspended for measurement of isometric force in organ chambers. Concentration–response curves to raloxifene (10−9–10−5M) were obtained in rings at baseline tension or following contraction with prostaglandin (2 × 10−6M) in the absence or presence of NG-monomethyl-l-arginine (l-NMMA) (nitric oxide synthase inhibitor), 1H-(1.2.4) oxadiazolo (4,3-A) quinoxalin-1-one (ODQ, soluble guanylate cyclase inhibitor), tetraethylammonium acetate (TEA; potassium channel blocker), or indomethacin (cyclooxygenase inhibitor). Raloxifene caused acute, concentration-dependent relaxations that were greater in rings with than in rings without endothelium from both groups. The l-NMMA significantly inhibited relaxations to raloxifene in rings with endothelium from ovariectomized females whereas TEA only inhibited relaxations in rings with endothelium from intact female pigs. ODQ and indomethacin significantly inhibited relaxations in rings with endothelium from both groups. These results suggest that raloxifene acutely relaxes femoral veins through release of endothelium-derived factors and by direct stimulation of vascular smooth muscle cells. Whether nitric oxide or potassium channel activation contributes to relaxations by raloxifene may depend on ovarian hormonal status of the animal.

Cyclic nucleotides and production of prostanoids in human varicose veins

OBJECTIVE Experiments were designed to determine the production of prostacyclin and thromboxane and the activation of cyclic nucleotides in human varicose and nonvaricose veins and to determine whether these second messenger pathways were differentially activated by the venotropic extract of Ruscus aculeatus. METHODS The experiments were designed to characterize the activity of cyclic nucleotides and the production of prostaglandins in human varicose and nonvaricose veins. Segments of the greater saphenous veins and the adjacent tributaries were obtained from patients who underwent vein stripping and excision of primary varicose veins. The saphenous veins from the patients who underwent peripheral arterial bypass grafting were used as controls. The segments of veins were incubated in Krebs-Ringer bicarbonate solution in the presence of venotropic extract of Ruscus aculeatus (10(-3) g/mL) or in water-miscible organic solvent (dimethyl sulfoxide, 10(-3) g/mL), for 1, 5, and 10 minutes at 37 degrees C. The nonspecific phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine, 10(-4) g/mL) was used to block cyclic nucleotide degradation in some samples. Tissue and media samples were collected. Tissue concentrations of both cyclic adenosine monophosphate and cyclic guanosine monophosphate (cAMP and cGMP, respectively) and media concentrations of 6-ketoprostaglandin-F(1)(alpha) (the stable metabolite of prostacyclin) and thromboxane B(2) (the stable metabolite of thromboxane A(2)) were measured by means of radioimmunoassay. Cyclooxygenase 2 was measured with Western blot analysis. RESULTS The varicose veins showed greater levels of cAMP but not of cGMP at all time points as compared with the control veins. Prostanoid production was not significantly altered in the varicose veins. Stimulation with Ruscus aculeatus increased the cAMP concentration in the varicose veins but did not affect the cGMP levels. The ratio between 6-ketoprostaglandin-F(1)(alpha) and thromboxane B(2) was two-fold greater in the varicose veins as compared with the control veins. In the presence of the extract, the ratio of 6-ketoprostaglandin-F(1)(alpha) and thromboxane B(2) was identical in both types of veins. Cyclooxygenase 2 was not present in either the control or the varicose veins. CONCLUSION These results suggest that cAMP levels are elevated in varicose veins and that they can be altered with drug treatment in varicose veins. This chemical pathway may be considered as a modulatory target to affect contraction with venotropic drugs.

Cofactors of constitutive nitric oxide synthase and endothelium-dependent relaxations in canine femoral veins

Summary Enzymatic production of nitric oxide (NO) in arterial endothelial cells requires the cofactors calmodulin and nicotinamide adenine dinucleotide phosphate (NADPH). Experiments were designed in investigate whether these cofactors are required for endothelium-dependent relaxations in canine femoral veins. Veins were removed from anesthetized dogs and cut into rings. Endothelium was deliberately removed from some rings. All rings were incubated with indomethacin (1

Time and dose effect of transdermal nicotine on endothelial function

10 -5 M). In separate sets of experiments, rings were incubated withcalmidazolium(1

Selected Contribution: Effects of sex and ovariectomy on responses to platelets in porcine femoral veins

10-5 M), fendiline (1

Interactions of Ruscus-extract with endothelin-receptors in human varicose veins

10-6M), both inhibitors of calmodulin or diphenylene-iodonium (1