Oral treatment with an antioxidant (raxofelast) reduces oxidative stress and improves endothelial function in men with Type II diabetes

Aims/hypothesis. To determine whether raxofelast, a new water soluble antioxidant decreases oxidative stress and improves endothelial function in men with Type II (non-insulin dependent) diabetes mellitus. Methods. We treated ten normotensive, normocholesterolaemic men with Type II diabetes and as controls ten healthy men matched with them for age with raxofelast (600 mg twice daily) for 1 week. Plasma 8-epi-PGF₂α, a non-enzymic oxidation product of arachidonic acid was measured by gas chromatography/mass spectrometry as an index of oxidative stress. Forearm vasodilator responses to brachial artery infusion of acetylcholine (7.5, 15 and 30 μg min^–1) and of the nitric oxide donor nitroprusside (1, 3 and 10 μg min^–1) were measured by strain gauge plethysmography. Results. Plasma concentrations of 8-epi-PGF₂α were greater in diabetic than in control men (0.99 ± 0.20 vs 0.18 ± 0.01 nmol l^–1, means ± SEM, p < 0.001) and fell after raxofelast (from 0.99 ± 0.20 to 0.47 ± 0.07 nmol l^–1, p < 0.05) in diabetic men but not in control men. Blood flow responses to acetylcholine were lower (p < 0.05) in diabetic than in control men (7.4 ± 1.0 vs 12.9 ± 2.3 ml · min^–1· 100 ml^–1 for the highest dose). In diabetic men, but not in control men, raxofelast increased (p < 0.05) blood flow responses to acetylcholine (from 7.4 ± 1.0 ml · min^–1· 100 ml^–1 to 11.3 ± 2.3 ml · min^–1· 100 ml^–1 at highest dose). Blood flow responses to nitroprusside were similar in control and diabetic men and in both groups were similar before and after raxofelast. Conclusion/interpretation. Oral treatment with raxofelast for 1 week reduces oxidative stress and improves endothelial function in men with Type II diabetes. [Diabetologia (2000) 43: 974–977] Received: 14 October 1999 and in revised form: 28 May 2000     

Effect of acute and chronic ethanol treatment on renal prostaglandins in the rat

To study the effects of ethanol on renal prostaglandins (PGs), we gave rats a dose of 3.0 g/kg body weight either as a single IP injection (acute treatment) or daily IP injections of the same dose for 23 consecutive days (chronic treatment). The availability of PG precursors was evaluated from the post mortem accumulation of PGF_2α in kidney as determined by gas chromatography—mass spectrometry, and the renal excretion of PGF_2α was measured by radioimmunoassay. Acute ethanol treatment had no dramatic effect on either tissue levels or urinary excretion rate of PGF_2α but chronic ethanol treatment significantly lowered renal PGF_2α levels. In another experiment we employed liquid ethanol diets and a pair feeding technique for 12 days to achieve tolerance and physical dependence on ethanol. The levels of PGF_2α and 6-keto PGF_1α were measured in kidney in rats killed at 2, 6, and 12 days post-treatment. The kidney levels of both prostaglandins were lowered throughout the period of chronic ethanol exposure but returned to normal within five days after withdrawal. Thus, chronic but not acute ethanol treatment leads to a depletion of the renal stores of prostaglandin precursors in the rat.     

Indomethacin and diclofenac sodium increase sodium and water excretion after extracellular volume expansion in the rabbit

The renal effects of an acute extracellular fluid volume expansion (50 ml Ringer/kg body weight/60 min) were studied in aldosterone-treated (100 μg/kg), anesthetized rabbits with and without pretreatment with either indomethacin (3.0 mg/kg) or diclofenac sodium (3.0 mg/kg), two different inhibitors of renal prostaglandin (PG) biosynthesis. In controls (n = 7), the volume expansion increased urine flow from 1.5 ± 0.24 to 6.1 ± 0.5 (S.E.) ml/min/100 g kidney weight and sodium excretion from 0.15 ± 0.03 to 0.99 ± 0.10 mmol/min/100 g. PAH and insulin clearance increased by 42 and 58%, respectively, while plasma renin activity and urinary excretion of PGF_2α-like immunoreactivity were reduced (P < 0.05). In aninals pretreated with indomethacin (n = 6) or diclofenac sodium (n = 6), the diuresis and the natriuresis following volume expansion were significantly increased about two-fold over controls, whereas PAH and inulin clearance, plasma renin activity and hematocrit did not differ from controls. Both drugs were found to reduce urinary excretion of PGF_2α-like immunoreactivity by 75–95% throughout the experiment. The results indicate that diclofenac sodium, indomethacin and extracellular volume expansion enhance sodium and water excretion partly by suppression of a PG sensitive reabsorption process in the kidney.     

Subcellular fractionation of cat submandibular gland: Comparative studies on the distribution of acetylcholine and vasoactive intestinal polypeptide (VIP)

In previous studies, evidence has been obtained for the presence of vasoactive intestinal polypeptide (VIP) in presumptive cholinergic neurons innervating the exocrine glands in the cat. In the present study, an attempt was made to define the storage sites of these two compounds in the cat submandibular gland using subcellular fractionation techniques. Particulate VIP was preferentially found in dense fractions (0.78–0.97 M sucrose) of a density gradient. Particle-bound acetylcholine showed a bimodal distribution in the gradient with relative enrichment in a dense fraction (0.87 M sucrose) but mainly in lighter fractions (0.28–0.44 M sucrose). More than 50% of all acetylcholine was recovered in a soluble form. For comparison, noradrenaline was also analysed and found in paniculate form in fractions ranging between 0.44–0.78 M sucrose. The electron microscopic analysis revealed presence of i.a. small clear vesicles in the lighter fractions, whereas the fractions rich in VIP contained i.a. many larger vesicles, sometimes with an electron-dense core. In agreement with earlier ultrastructural immunocytochemical studies on intact tissue, the present results support the view that VIP is present in large dense-cored vesicles. Most of the particulate acetylcholine seems to be localized in small clear vesicles, although a small proportion could be associated with large vesicles. Whether acetylcholine and VIP coexist in such large vesicles or whether separate populations of large vesicles exist, remains to be elucidated.     

Propranolol in the treatment of opiate dependence — a controlled study

Two doubleblind placebo controlled experiments designed to elucidate the alleged narcotic blocking effect of propranolol were performed. In the first experiment, propranolol 40 mg or 20 mg was given together with methadone during the acute withdrawal phase of opiate addiction. The second experiment assessed whether 10 mg of propranolol, given 2 hrs before 30 mg of morphine i.v., reduced the euphoric effects of the latter drug. In none of the experiments could narcotic blocking effects be detected. The group receiving 40 mg propranolol during detoxification exhibited the highest proportion of patients staying for the whole prescribed detoxification period.     

Inhibition of cigarette smoke-induced oedema in the nasal mucosa by capsaicin pretreatment and a substance P antagonist

The effect of cigarette smoke on vascular permeability in the rat nasal mucosa was studied using the Evans blue extravasation method. Exposure to smoke from cigarettes induced a significant extravasation of Evans blue in the nasal mucosa of normal rats, suggesting an increased vascular permeability to plasma proteins. The oedema response was correlated to tar, nicotine and vapour phase components in the smoke. The smoke-induced permeability effect was abolished in rats pretreated neonatally with capsaicin. Also, systemic or local pretreatment with [D-Arg, D-Pro, D-Trp, Leu]Substance P, a substance P antagonist, inhibited the permeability response to cigarette smoke. Insertion of a glass-fibre filter, which removes the particulate phase of the smoke (including nicotine), did not significantly reduce the permeability response. The present findings suggest that the smoke-induced oedema in the rat nasal mucosa is not caused by nicotine but by vapour-phase irritants, which activate capsaicin-sensitive C-fibre afferents. These neurons then release agents such as substance P or a related tachykinin which increase permeability to plasma proteins.     

Time course of breath acetaldehyde concentrations during intravenous infusions of ethanol in healthy men

A gas chromatographic method was developed for the quantitative determination of acetaldehyde in expired alveolar air of human subjects. A rapid and direct gas-sampling system allow serial determinations and avoid the need for correcting for sample losses or poor recoveries. This method was evaluated in experiments with healthy men during different modes of intravenous infusion of ethanol. The time course of breath-ethanol and breath-acetaldehyde concentrations were used to estimate the coexisting blood levels. Blood acetaldehyde concentration (y) was about 2000 times less than blood ethanol (x) and the values were highly correlated r = 0.90 +/- 0.05, P less than 0.001. The regression equation was y = 2.0 + 0.303x; the intercept was significantly different from zero. Breath acetaldehyde faithfully followed the changes in breath and blood ethanol concentrations for widely varying rates of ethanol infusion.