Effects of single sessions of low-intensity continuous and moderate-intensity intermittent exercise on blood lipids in the same endurance runners.

The factors responsible for the acute effects of exercise on blood lipids are not well known, and there have been few studies comparing different kinds of exercise in the same population. The concentration of blood lipids was evaluated in this study at the end and at post-24h of two 14km/90min single exercise sessions: continuous exercise (CE) at 44.5+/-5.6% VO(2max) and intermittent exercise (IE) at 39-72% VO(2max), in subjects with high levels of aerobic training. Fourteen male athletes (endurance runners) took part in this study and each completed a 24h dietary record. The O(2) uptake and CO(2) production were recorded, and blood lactate and blood lipids were measured. The results showed that triacylglycerols were not modified by any kind of exercise. Total cholesterol was increased at the end of both exercises: 7.04% for CE (p<0.001) and 4.23% for IE (p=0.001). High-density lipoprotein cholesterol was increased at the end of IE: 11.38% (p=0.03) and low-density lipoprotein cholesterol was increased only at the end of CE: 7.45% (p=0.006). The increase of lipids for CE was negatively correlated with aerobic fitness indicators (heart rate and %HRmax at lactate threshold), and was positively associated with energy expenditure. For IE, %HRmax and lactate were negatively correlated, and the respiratory exchange ratio was positively correlated, with the lipid increase. We conclude that in trained male athletes, a 14km run in 90min induced different changes of lipid profile if the exercise was done continuously or intermittently, and that in CE the extent of these increases was influenced by aerobic fitness.

Endothelium-dependent effects of the ethanolic extract of the mistletoe Psittacanthus calyculatus on the vasomotor responses of rat aortic rings.

The mistletoe Psittacanthus calyculatus (Loranthaceae) is used in Mexican traditional medicine for the treatment of hypertension. In the present study the effects of a crude ethanolic extract of this mistletoe, on the vasomotor reactivity of superfused rat aortic rings (with or without a functional endothelium) were analyzed. Either in the absence or in the presence of L-NAME or indomethacin, the extract (12.5-800 microg/ml) had no effect on the basal tone of both types of rings. In phenylephrine-precontracted rings, low concentrations of the extract (up to 300 microg/ml) induced a small additional tension development in both types of rings; however, the tension increase was slightly larger in rings having an intact endothelium. At higher concentrations (400-800 microg/ml), the extract relaxed, concentration-dependently, phenylephrine-precontracted rings with an intact endothelium. This relaxation was completely reverted by the addition of L-NAME. When the extract was applied in the continuous presence of L-NAME to phenylephrine-precontracted rings, instead of a relaxation a marked additional tension development occurred. Indomethacin did not modify the relaxation induced by the extract. The results indicate that the ethanolic extract of this mistletoe induces, predominantly, an endothelium-dependent relaxation which seems to be mediated by the synthesis/release of nitric oxide.

Effects of the ethanolic extract of Spirulina maxima on endothelium dependent vasomotor responses of rat aortic rings.

Dietary Spirulina decreases, endothelium-dependently, the responses to vasoconstrictor agonists and increases the endothelium-dependent, agonist-induced, vasodilator responses of rat aorta rings. The aim of this study was to analyze, in vitro, the effects of a raw ethanolic extract of Spirulina maxima on the vasomotor responses of rat aortic rings to phenylephrine and to carbachol. On rings with endothelium, the extract produced the following effects: (a) a concentration-dependent (60-1000 microg/ml) decrease of the contractile response to phenylephrine; (b) a rightward shift and a decrease in maximal developed tension, of the concentration--response curve to phenylephrine; (c) a concentration dependent relaxation of phenylephrine-precontracted rings. These effects were blocked by L-NAME, and not modified by indomethacin. The extract had no effect on the concentration-response curve to carbachol of rings with endothelium. On endothelium-denuded rings the extract caused a significant rightward shift of the concentration response curve to phenylephrine without any effect on maximal tension development. In the presence of the extract, indomethacin induced a marked decrease in the maximal phenylephrine-induced tension of endothelium-denuded rings. These results suggest that the extract increases the basal synthesis/release of NO by the endothelium and, also, the synthesis/release of a cyclooxygenase-dependent vasoconstricting prostanoid by vascular smooth muscle cells.

Studies on the preventive effect of Spirulina maxima on fatty liver development induced by carbon tetrachloride, in the rat.

The aim of the present work was to assess if the feeding of either the oil extract of Spirulina maxima or of its defatted fraction would prevent fatty liver development, induced in rats by a single intraperitoneal dose of carbon tetrachloride (CCl4). Liver and serum lipids were evaluated 4 days after treatment with this agent. Concentration of liver lipids did not differ in rats fed on a purified diet either without or with one of the fractions of Spirulina, except for total cholesterol, which showed a slight increase in the group receiving the oil extract of Spirulina. However, after CCl4 treatment, liver total lipids and triacylglycerols were significantly lower in rats fed on a diet containing any fraction of Spirulina (defatted or the oil fraction) than in rats without Spirulina in their diet. Furthermore, the increased liver cholesterol values, induced by CCl4 treatment, were not observed in rats receiving Spirulina. In addition, rats receiving whole Spirulina in their diet and treated only with the vehicle showed an increase in the percentage of HDL values. The changes in VLDL and LDL induced by CCl4 treatment were not observed in the whole Spirulina group. Furthermore, after CCl4 treatment the values of the liver microsomal thiobarbituric acid-reactive substances were lower in the whole Spirulina group than in the control group. These results support the potential hepatoprotective role of Spirulina.

Spirulina maxima prevents induction of fatty liver by carbon tetrachloride in the rat.

The aim of the present work was to assess the capacity of Spirulina maxima to prevent fatty liver development induced in rats by an intraperitoneal single dose (1 ml/kg) of carbon tetrachloride. Liver and serum lipids were quantified two or four days after treatment with this agent. Liver lipid concentration did not differ in rats fed on a purified diet with or without Spirulina. However, after carbon tetrachloride treatment, liver triacylglycerols were significantly lower in rats fed on a diet with Spirulina 5% than in rats without Spirulina in their diet (P < 0.05). Furthermore, the increased liver cholesterol values, induced by carbon tetrachloride treatment, were not observed in rats that received Spirulina. These results support the potential hepatoprotective role of Spirulina.

Effects of dietary Spirulina maxima on endothelium dependent vasomotor responses of rat aortic rings.

The aim of this study was to evaluate the effects of Spirulina maxima on vasomotor responses of aorta rings from male Wistar rats fed on a purified diet. For this purpose, the animals (weighing 200-240 g) were allocated randomly in two groups. One receiving purified control diet (A) and the other receiving purified diet containing 5% Spirulina (B). Purified diets were according to American Institute of Nutrition guidelines and adjusted to Spirulina protein content. All animals were fed (20 g/day/rat) during two weeks, receiving water ad libitum and 12 h. light-dark cycles. Spirulina maxima effects were evaluated by concentration-response (CR) curves of aorta rings with or without endothelium to phenylephrine (PE), both in presence and absence of indomethacin (Indom) or indomethacin plus L-NAME (Indom. + L-NAME), and to carbachol (CCh). Aorta rings with endothelium from group B showed, relative to corresponding rings from group A: 1) a significant decrease in the maximal tension developed in response to PE. 2) this decrease was reverted by Indom. 3) Indom. + L-NAME induced an additional increase in the contractile responses to PE. 4) a significant shift to the left of the CR curve to CCh. No significant differences were observed in the tension developed in response to PE in rings without endothelium from either group. These results suggest that Spirulina maxima may decrease vascular tone by increasing the synthesis and release of both a vasodilating cyclooxygenase-dependent product of arachidonic acid and nitric oxide, as well as by decreasing the synthesis and release of a vasoconstricting eicosanoid from the endothelial cells.

Effects of acute and chronic estrogenic treatment on vasomotor responses of aortic rings from ovariectomized rats.

The effects of either chronic or acute estrogenic treatment on the "in vitro" vasomotor responses to phenylephrine (10(-9)-10(-5) M) and to carbachol (10(-9)-10(-5) M) of aortic rings excised from ovariectomized rats were analyzed. Chronic estrogenic treatment consisted in a single subcutaneous dose of 1 mumol estradiol 17-stearate. Effects of acute estrogenic treatment were evaluated by recording the responses of aortic rings excised from untreated ovariectomized rats both before and after the addition of 17 beta-estradiol to the superfusing solutions. In order to identify the endothelium-dependent responses each experiment was performed simultaneously on pairs of rings from the same aorta, one with and the other without functional endothelium. The contractile responses to phenylephrine of endothelium-intact vessels were attenuated by chronic estrogenic treatment; this attenuation was further increased by preincubation of the vessels with indomethacin and was reverted by N omega-nitro-L-arginine methyl ester. Either chronic or acute estrogenic treatment enhanced the carbachol-induced endothelium dependent relaxation of phenylephrine-precontracted rings. The results may be explained by assuming that estrogens increase the basal release of both nitric oxide and a cyclooxygenase-dependent vasoconstricting prostanoid as well as the receptor-mediated release of nitric oxide from the endothelium of the rat aorta.