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J R Huertas

Publications and source records attributed to J R Huertas.

33 records · Page 2Linked to original sources
PubMed1994

Peroxidative extent and coenzyme Q levels in the rat: influence of physical training and dietary fats.

Sport practice is widely recognized as capable of producing peroxidative damages, even of severe intensity. Dietary manipulations can also modify membrane susceptibility to peroxidation. In previous experiments we found that, while dietary virgin olive oil successfully protects mitochondrial and microsomal membranes from endogenous, xenobiotics-induced peroxidation, dietary polyunsaturated oils lead to increased peroxidative levels. In the latter conditions, cell machinery tries to counteract the structural and functional changes which have occurred, by modulating enzyme activities and concentrations, by increasing biosynthesis of coenzyme Q and by mobilizing cholesterol. In the present study we hypothesized that combining these two aspects could give useful information on the membrane response to peroxidation phenomena that daily occur throughout the lifespan. Rats fed different dietary oils as only fat source underwent a carefully designed training program and were killed at different times following acute or chronic exercise. Results show that peroxidation related to chronic training and to an acute bout of exercise sum up with peroxidative effects induced by dietary factors. The above mentioned phenomena occurred simultaneously with increased tissue levels of coenzyme Q, possibly triggered within a physiological reactive antioxidant strategy.

Aging↗
PubMed1993

Role of vasoactive intestinal polypeptide (VIP), secretin and gastrin in the genesis of the late exocrine pancreatic hypersecretion, food intake dependent in conscious dogs.

Plasma levels of vasoactive intestinal polypeptide (VIP), secretin and gastrin were studied in four saphenous vein-catheterized dogs during the first 12 h after ingestion of a standard solid meal. Under these conditions we found significant postprandial increases in secretion only, which rose from a basal value of 219 +/- 27 pg/ml to 449 +/- 66 pg/ml 60 min postprandial (p < 0.001), and remained elevated until 4 h after food intake. However, no increase was seen from 8 to 12 h in any of the hormones studied, indicating that they are not directly involved in the enhancement of exocrine pancreatic secretion during this period.

Animals↗
PubMed1992

Mitochondrial and microsomal cholesterol mobilization after oxidative stress induced by adriamycin in rats fed with dietary olive and corn oil.

The influence of three different dietary fats (8%) and of endogenous lipid peroxidation with regard to cholesterol concentrations in liver mitochondria and microsomes and in serum has been investigated in the rat. Although the different diet fat used did not produce any effect on serum cholesterol, it was possible to show that each experimental diet differently influenced the microsomal and mitochondrial levels of cholesterol. The highest mitochondrial and microsomal cholesterol content was found in case of diet supplemented with virgin olive oil and the lowest with rectified olive oil. An endogenous oxidative stress induced by adriamycin was able to produce a clear decrease in microsomal and mitochondrial cholesterol level and a sharp increase in serum concentration in all three groups. However, dietary fats and adriamycin had no effect on the microsomal and mitochondrial membrane viscosity as detected by fluorescence polarization. These results are consistent with the hypothesis that mitochondrial and microsomal cholesterol can exchange with exogenous pools when phospholipid peroxidation occurs.

Animals↗
PubMed1992

Adaptation of biliary response to dietary olive oil and sunflower-seed oil in dogs.

The effects of adaptation to dietary fat of different degrees of unsaturation (olive oil and sunflower oil) on bile secretion were studied in dogs at rest and after food intake. The animals were prepared with a bidirectional biliary cannula and a duodenal cannula to provide bile return. The two experimental groups were fed on diets containing 150 g fat/kg in the form of either olive oil (O) or sunflower-seed oil (S). The flow-rate under resting conditions and the patterns of response to food were similar in both experimental groups, although postprandial hypersection were significantly greater in volume and more prolonged in group O. No appreciable differences in concentration and output of biliary cholesterol or phospholipids were noted between the two groups. In contrast, the concentration and output of bile acids differed significantly both at rest and after food: concentration and output of bile acids were greater at rest in group S. However, after food intake, these responses were increased only in group O. The results suggest that the type of dietary fat affects biliary response to food, probably through differences in the contribution of the gall bladder in the two experimental groups.

Adaptation, Physiological↗
PubMed1992

Comparative effect of truncal vagotomy and pirenzepine on postprandial secretory response of exocrine pancreas in dogs.

The comparative effect of truncal vagotomy and associated pyloroplasty and orally administrated pirenzepine (75 mg, 1 h before food intake) on the exocrine pancreatic secretory response to food was studied in conscious dogs. Both pirenzepine administration and truncal vagotomy totally abolished the pancreatic hydromineral and organic secretory response to food intake while postprandial pH of intraduodenal content remained above 6. From the results of our study we conclude that the vago nerve must not be altered in order to assure a pancreatic response to food intake and that pirenzepine is as strong as truncal vagotomy in maintaining pH in postprandial intraduodenal content over 6.

Amylases↗
PubMed1992

[Cytochrome oxidase induction following oxidative stress produced by adriamycin in the heart of rats fed olive oil].

Cytochrome oxidase is extremely susceptible to modifications that could occur at membrane level such as, for example, the deep influence that cardiolipin has on its maximal activity. Moreover, even the different ratio of fatty acid species in cardiolipin molecule could affect cytochrome oxidase properties. The influence of dietary fat and of endogenous lipid peroxidation with regard to cytochrome c oxidase activity and cytochrome a+a3 concentrations in mitochondria from rat heart has been investigated. Whilst the endogenous oxidative stress led to increase the peroxidation products, detected by means of hydroperoxides and conjugated dienes determinations, the features of the lipid environment were not affected as shown by fluorescence polarization technique. However, the oxidative stress was able to induce a significant increase of cytochrome a+a3 level even if the phenomenon did not reach the same extent as in the case of previous investigations on rat liver. Moreover, the results vary with the different fat source used and this might indicate a possible involvement of different dietary fats in peroxidation mechanisms. Furthermore the data we have obtained enable us to confirm once more that an induction of the synthesis of cytochrome a+a3 might be related to an enhanced production of peroxides at membrane level.

Animals↗
PubMed1991

Cytochrome oxidase induction after oxidative stress induced by adriamycin in liver of rats fed with dietary olive oil.

The influence of different kinds of dietary fat (8%) and of endogenous lipid peroxidation with regard to cytochrome c oxidase activity and cytochrome a + a3 concentrations in mitochondria from rat liver has been investigated. It was possible to confirm that the dietary fat induced higher phospholipid degradation in mitochondrial membranes; moreover an endogenous oxidative stress induced by adriamycin was able to increase the peroxidative effects. We have found that the peroxidative effects could sometimes induce an apparent enhancement of cytochrome oxidase activity due to a significant increase of cytochrome a + a3 content. This finding lets us suppose that both changes in the lipid environment and some peroxidation damage could occur in the membrane as a consequence of the fat assumed. Furthermore we should suggest that an induction of the synthesis of cytochrome a + a3 might be related to an enhanced production of peroxides at membrane level.

Animals↗
PubMed1991

Changes in mitochondrial and microsomal rat liver coenzyme Q9 and Q10 content induced by dietary fat and endogenous lipid peroxidation.

The influence of different kinds of dietary fat (8%) and of endogenous lipid peroxidation with regard to coenzyme Q9 (CoQ9) and coenzyme Q10 (CoQ10) concentrations in mitochondria and microsomes from rat liver has been investigated by means of an HPLC technique. Although the different diet fats used did not produce any effect on microsomes, it was possible to show that each experimental diet differently influenced the mitochondrial levels of CoQ9 and CoQ10. The highest mitochondrial CoQ content was found in case of a diet supplemented with corn oil. An endogenous oxidative stress induced by adriamycin was able to produce a sharp decrease in mitochondrial CoQ9 levels in the rats to which corn oil was administered. The results suggest that dietary fat ought to be considered when studies concerning CoQ mitochondrial levels are carried out.

Animals↗
PubMed1991

Effect of dietary fat on biliary lipids composition of gallbladder bile in miniature swine (Sus scrofa).

1. Weaning animals (34 days old) were fed for 6 months with four diets that differed only in the quantity and quality of fat sources (control group 3.2% (w/w), lard-fed group 7.6% (w/w), olive-oil-fed group 10.4% (w/w), and sunflower-oil-fed group 10.5% (w/w). Samples were collected and assessed after animals were killed at 6 months of age. 2. Our results show that the quality of fat did not alter biliary lipids composition of the gallbladder bile composition in miniature swine after 6 months adaptation to the diet, except for a significant increase of the phospholipid concentration in the lard-fed group with regard to the control group. 3. The highest and lowest bile cholesterol saturation indices were observed in sunflower and lard-fed groups, respectively showing in all cases saturation indices far from the saturation point.

Adaptation, Physiological↗
PubMed1991

Postprandial modifications of plasma secretin levels during pancreatic secretion in dogs.

In dogs with a direct pancreatic fistula, a duodenal cannula and a catheter in a saphenous vein, plasma secretin levels, changes in the flow, bicarbonate and chloride concentrations of the exocrine pancreatic secretion as well as in the pH of intraduodenal content have been studied 12 hours after the ingestion of a standard diet. Under these conditions the pancreatic secretion showed a biphasic response with a maximum flow and bicarbonate concentration during the 0-4 and 8-12 h postprandial periods. This coincided with a marked decrease of pH in the intraduodenal content, with values close to 4.5. On the other hand, during the first postprandial hour, plasma secretin values increased from basal ones (218.66 +/- 27 pg/ml) to 448.94 +/- 66 pg/ml, remaining elevated for four hours after the meal ingestion. However, no increase occurred between 8-12 h when intraduodenal pH reached values below 4.5. This study indicated that: 1) plasma secretin levels increased significantly (P less than 0.05) after the ingestion of a standard solid diet, and 2) determinants liberating secretin were not only the presence of a duodenal pH below 4.5, but probably the presence of some macronutrients from the meal.

Animals↗
PubMedDate not supplied

Effects of adaptation to diets enriched with saturated, monounsaturated and polyunsaturated fats on lipid and serum fatty acid levels in miniature swine (Sus scrofa).

A total of 37 miniature swine (Sus scrofa) was fed with three diets of 9% fat content, differing only in the quality of the fat source (sunflower oil, olive oil and lard fat). Three groups of animals were fed for a 3 month period, and three other groups were fed for a 12 month period. After the two experimental periods, the influence of the diet on serum lipids and serum fatty acids was studied. In the short term, the serum cholesterol level was higher in the lard group, but with time, it undergoes a significant increase in the sunflower group, due to increases both in HDL-C and in LDL-C. In the olive oil group, LDL-C hardly varies with time, while HDL-C tends to decrease. In the lard group, LDL-C increases and HDL-C decreases. The atherogenic index is, in the long term, lower in the lard group and higher in the polyunsaturated fat group. The fatty acid composition of serum lipids in the long term shows a greater saturation index (SI) for the sunflower group and lard group, an increase in monounsaturated fatty acids in the olive oil group, and a higher percentage of linoleic acid in the sunflower group.

Adaptation, Physiological↗
PubMedDate not supplied

Late postprandial pancreatic secretion periods in conscious dogs. Effect of vagotomy.

It is well established that, in the dog, the exocrine pancreatic secretion in response to food intake is a two-phased mechanism with a first phase during 0-4 h period and a second one during 8-12 h period. In the present study we have investigated the role played by the vagus nerve in the genesis of this late pancreatic hypersecretion (second phase) in dogs with truncal vagotomy and pyloroplasty. Truncal vagotomy totally suppressed the first phase of the pancreatic secretion; it did not abolish the second postprandial phase but it increased its latency by delay of 4 hours. In fact, during the 12-18 h period a pancreatic hypersecretory response was evidenced after vagotomy which appeared to be statistically significant as compared to basal values (P less than 0.001). Our results indicate that the vagus nerve does not play a role in the genesis of the late hypersecretory second phase.

Animals↗
PubMedDate not supplied

Effect of dietary fat composition on biliary cholesterol saturation index in dogs.

In dogs, the effect of dietary fat on bile cholesterol saturation index and the evolution of molar percentages of biliary lipids have been studied in both fasting and postprandial periods after a long-term adaptation period to diets which only differ in their lipidic source (olive oil and sunflower oil). It has been observed that for similar bile cholesterol saturation indexes in both groups, dietary fat altered differently biliary lipid composition through a double mechanism which involved bile acids and phospholipids. Dietary fat is postulated to affect differently the lipidic composition of bile as well as the biliary tree motility both during interdigestive and postprandial periods.

Adaptation, Physiological↗
PubMedDate not supplied

Distal ileum resection totally suppresses the late pancreatic postprandial hypersecretion in conscious dogs.

Exocrine pancreatic secretion and serum levels of secretin, vasoactive intestinal peptide (VIP) and gastrin within postprandial 12 hours have been studied in dogs that have undergone a partial ileum resection (last 25 cm) 4 weeks before. In these conditions the following effects were observed: 1) the flow of pancreatic juice secreted after the food intake (1-4h period) was strictly similar to the flow described in intact dogs which did not suffer that surgical manipulation but it came back to its basal value more rapidly; 2) there were no effects regarding the postprandial hormonal pattern; 3) the late pancreatic hypersecretion period that is usually observed in intact dogs within the postprandial 8-12 h period, completely disappeared. These results allow to conclude that the mechanisms inducing the late hypersecretion process that usually takes place within the postprandial 8-12 h in dogs are generated in the distal ileum.

Animals↗