RESUMEN
The purpose of this study was to modify the amount of 22:4 n-6, 22:5 n-6 and 20:5 n-3 in cardiac phospholipids and to evaluate the influence of these changes on the functioning of working rat hearts and mitochondrial energy metabolism under normoxic conditions and during postischemic reperfusion. The animals were fed one of these four diets: (i) 10% sunflower seed oil (SSO); (ii) 10% SSO + 1% cholesterol; (iii) 5% fish oil (FO, EPAX 3000TG, Pronova) + 5% SSO; (iv) 5% FO + 5% SSO + 1% cholesterol. Feeding n-3 PUFA decreased n-6 PUFA and increased n-3 PUFA in plasma lipids. In the phospholipids of cardiac mitochondria, this dietary modification also induced a decrease in the n-6/n-3 PUFA ratio. Cholesterol feeding induced marked hepatic steatosis (HS) characterized by the whitish appearance of the liver. It also brought about marked changes in the fatty acid composition of plasma and mitochondrial phospholipids. These changes, characterized by the impairment of deltaS- and delta6-desaturases, were more obvious in the SSO-fed rats, probably because of the presence of the precursor of the n-6 family (linoleate) in the diet whereas the FO diet contained large amounts of eicosapentaenoic and docosahexaenoic acids. In the mitochondrial phospholipids of SSO-fed rats, the (22:4 n-6 + 22:5 n-6) to 18:2 n-6 ratio was decreased by HS, without modification of the proportion of 20:4 n-6. In the mitochondrial phospholipids of FO-fed rats, the amount of 20:5 n-3 tended to be higher (+56%). Cardiac functioning was modulated by the diets. Myocardial coronary flow was enhanced by HS in the SSO-fed rats, whereas it was decreased in the FO-fed animals. The rate constant k012 representing the activity of the adenylate kinase varied in the opposite direction, suggesting that decreased ADP concentrations could cause oxygen wasting through the opening of the permeability transition pore. The recovery of the pump function tended to be increased by n-3 PUFA feeding (+22%) and HS (+45%). However, the release of ascorbyl free radical during reperfusion was not significantly modified by the diets. Conversely, energy production was increased by ischemia/reperfusion in the SSO group, whereas it was not modified in the FO group. This supports greater ischemia/reperfusion-induced calcium accumulation in the SSO groups than in the FO groups. HS did not modify the mitochondrial energy metabolism during ischemia/reperfusion. Taken together, these data suggest that HS- and n-3 PUFA-induced decrease in 22:4 and 22:5 n-6 and increase in 20:5 n-3 favor the recovery of mechanical activity during post-ischemic reperfusion.
Asunto(s)
Grasas de la Dieta/farmacología , Ácidos Grasos Insaturados/farmacología , Corazón/efectos de los fármacos , Hígado/patología , Mitocondrias Cardíacas/efectos de los fármacos , Isquemia Miocárdica/metabolismo , Daño por Reperfusión/metabolismo , Adenina/metabolismo , Animales , Aorta/efectos de los fármacos , Aorta/fisiología , Ácido Ascórbico/metabolismo , Peso Corporal/efectos de los fármacos , Gasto Cardíaco/efectos de los fármacos , Respiración de la Célula/efectos de los fármacos , Colesterol en la Dieta/farmacología , Circulación Coronaria/efectos de los fármacos , Grasas de la Dieta/sangre , Ácidos Grasos Insaturados/sangre , Aceites de Pescado/farmacología , Radicales Libres/metabolismo , Corazón/fisiología , Hígado/efectos de los fármacos , Hígado/metabolismo , Mitocondrias Cardíacas/química , Mitocondrias Cardíacas/metabolismo , Isquemia Miocárdica/patología , Tamaño de los Órganos/efectos de los fármacos , Oxígeno/farmacología , Palmitoilcarnitina/metabolismo , Fosfatos/metabolismo , Aceites de Plantas/farmacología , Ácido Pirúvico/metabolismo , Ratas , Daño por Reperfusión/patología , Aceite de GirasolRESUMEN
The respective roles of exogenous polyunsaturated fatty acids on the lipid composition, physiological properties and enzyme release was investigated on isolated cardiac muscle cells in normoxia and hypoxia. Rat neonatal ventricular myocytes were grown for 5 days in conventional serum-supplemented medium. Cells were then incubated for 24 h in fully chemically-defined media featuring a balanced fatty acid composition containing either linoleic acid (18:2 n-6) or linolenic acid (18:3 n-3) as sole polyunsaturated fatty acid source. Transmembrane potentials were monitored with microelectrodes and contractions with a photoelectric device. The radio of n-6 to n-3 phospholipid fatty acids increased from 6.3 in control cells to 20.2 in cells exposed to n-6 fatty acids (SM6) and decreased to 1.4 in those exposed to n-3 fatty acids (SM3). These modifications had no influence on the electrical and mechanical activities and on automaticity in normoxic conditions. The action potential depression under hypoxia was less severe in SM6 cells, whereas there was a better electrophysiological recovery upon reoxygenation in SM3 cells. However, the loss of lactate dehydrogenase during sustained hypoxic treatment was not affected by changes in phospholipid fatty acid pattern. These results suggest that the effect of the polyunsaturated fatty acid balance depends on the cellular function under study and on the environmental conditions.
Asunto(s)
Ácidos Grasos/análisis , Miocardio/citología , Fosfolípidos/análisis , Animales , Células Cultivadas , Medios de Cultivo/farmacología , Electrofisiología , Ventrículos Cardíacos/citología , Hipoxia/enzimología , Hipoxia/fisiopatología , L-Lactato Deshidrogenasa/metabolismo , Contracción Miocárdica , Miocardio/análisis , Miocardio/patología , Ratas , Ratas EndogámicasRESUMEN
Phospholipid catabolism is thought to be one of the critical events in membrane injury during heart ischemia. In this work, the enzymes involved in phospholipid metabolism were studied in purified cultured ventricular myocytes in normoxic and hypoxic conditions. Purified ventricular myocytes exhibited an alkaline phospholipase A activity which had sn-2 specificity and which was calcium dependent, and an acid phospholipase A activity with sn-1 specificity. These cells also exhibited lysophospholipase and acyl-CoA/lysophosphatidylcholine acyltransferase activities. Oxygen deprivation of the myocardial cells for 4 h resulted in a sharp reduction of both phospholipase A2 and A1 activities. The activities of the other lipolytic enzymes were unaffected by hypoxia. Although hypoxia resulted in a marked increase of lactate dehydrogenase leakage in the bathing fluid, no additional release of the lipolytic enzymes and mitochondrial enzyme was observed. However, we noted an important alkaline phospholipase A2 leakage during normoxia. It is suggested that ventricular myocytes, under hypoxia, tend to prevent phospholipid degradation by reducing their phospholipase A activities.
Asunto(s)
Hipoxia/metabolismo , Miocardio/enzimología , Fosfolípidos/metabolismo , 1-Acilglicerofosfocolina O-Aciltransferasa/metabolismo , Animales , Animales Recién Nacidos , Células Cultivadas , Ventrículos Cardíacos/enzimología , Isoenzimas/metabolismo , Lisofosfolipasa/metabolismo , Fosfolipasas A/metabolismo , Fosfolipasas A2 , Ratas , Valores de ReferenciaRESUMEN
Two populations of Wistar rats from the same strain were fed two commonly used commercial chows. The yields of myocardial cells for primary culture obtained from neonatal rats in these 2 populations were significantly different. This effect is strickly caused by diet used during pregnancy and is quickly reversible from one pregnancy to the following one in the same females. This diet effect is limited to the yield in cardiomyoblasts and cultures were not found different after 5 days in the same medium.
Asunto(s)
Dieta , Intercambio Materno-Fetal , Miocardio/citología , Animales , Animales Recién Nacidos , Células Cultivadas , Femenino , Embarazo , Ratas , Ratas EndogámicasRESUMEN
Neonatal rat heart cells cultivated in either of two different media which varied only in their serum supplements were transferred to chemically defined medium (Ham's F10) for 24 h before measuring a variety of parameters. The 24-h period of exposure to chemically defined medium was not sufficient to reverse the effects imposed on the cells by the serum used in the first phase of growth. The cells differed in rate and duration of action potentials and contractions. The initial serum composition affected the response of the cells to calcium deficiency. Studies involving the effects of pharmaceutical reagents such as isoproterenol were also influenced by the serum. In attempting to determine the cause and possible mechanism, it was found that mitochondrial membrane permeability for nitroblue tetrazolium (NBT) was unchanged. Although the serum supplements differed in fatty acid composition, the fatty acid profiles of the cell phospholipids were relatively constant. We conclude that the function of the cells is affected by the growth environment, particularly serum; that a short exposure to a uniform chemically defined medium is not sufficient to reverse these effects; and that the differences in effects are not the result of changes in the fatty acid composition of the whole cell phospholipids nor in mitochondrial membrane permeability as measured by NBT.
Asunto(s)
Medios de Cultivo/farmacología , Corazón/fisiología , Miocardio/citología , Potenciales de Acción/efectos de los fármacos , Animales , Fenómenos Fisiológicos Sanguíneos , Calcio/farmacología , Permeabilidad de la Membrana Celular/efectos de los fármacos , Grasas de la Dieta/farmacología , Ácidos Grasos/análisis , Corazón/efectos de los fármacos , Membranas Intracelulares/efectos de los fármacos , Isoproterenol/farmacología , Mitocondrias Cardíacas/efectos de los fármacos , Mitocondrias Cardíacas/metabolismo , Nitroazul de Tetrazolio/metabolismo , Fosfolípidos/metabolismo , Ratas , Ratas Endogámicas , Sarcolema/efectos de los fármacosRESUMEN
The histopathological status and histologically demonstratable succinate dehydrogenase activity were evaluated on contiguous heart sections of rats fed low erucic acid rapeseed oil for 18 weeks. The histologically demonstratable SDH activity was quantified and could be related with the severity of the lesion at the same location. These results were discussed in terms of effects of dietary fat on mitochondria.