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1.
Clinics ; 66(12): 2105-2111, 2011. ilus
Article Dans Anglais | LILACS | ID: lil-609009

Résumé

OBJECTIVES: Aerobic exercise training prevents cardiovascular risks. Regular exercise promotes functional and structural adaptations that are associated with several cardiovascular benefits. The aim of this study is to investigate the effects of swimming training on coronary blood flow, adenosine production and cardiac capillaries in normotensive rats. METHODS: Wistar rats were randomly divided into two groups: control (C) and trained (T). An exercise protocol was performed for 10 weeks and 60 min/day with a tail overload of 5 percent bodyweight. Coronary blood flow was quantified with a color microsphere technique, and cardiac capillaries were quantified using light microscopy. Adenine nucleotide hydrolysis was evaluated by enzymatic activity, and protein expression was evaluated by western blot. The results are presented as the means ± SEMs (p<0.05). RESULTS: Exercise training increased the coronary blood flow and the myocardial capillary-to-fiber ratio. Moreover, the circulating and cardiac extracellular adenine nucleotide hydrolysis was higher in the trained rats than in the sedentary rats due to the increased activity and protein expression of enzymes, such as E-NTPDase and 59- nucleotidase. CONCLUSIONS: Swimming training increases coronary blood flow, number of cardiac capillaries, and adenine nucleotide hydrolysis. Increased adenosine production may be an important contributor to the enhanced coronary blood flow and angiogenesis that were observed in the exercise-trained rats; collectively, these results suggest improved myocardial perfusion.


Sujets)
Animaux , Mâle , Rats , Adaptation physiologique/physiologie , Adénosine/biosynthèse , Pression sanguine/physiologie , Vaisseaux capillaires/physiologie , Circulation coronarienne/physiologie , Conditionnement physique d'animal/physiologie , Vaisseaux capillaires/enzymologie , Espace extracellulaire/enzymologie , Répartition aléatoire , Rat Wistar , Natation/physiologie
2.
Arch. Inst. Cardiol. Méx ; 65(2): 107-14, mar.-abr. 1995. ilus
Article Dans Espagnol | LILACS | ID: lil-167507

Résumé

Se estudiaron los efectos de la adenosina (ADO) sobre el automatismo y las oscilaciones post-potencial de fibras de Purkinje de corazones de perro. Se emplearon concentraciones de ADO desde 10-8 hasta 10-5 M. Se obtuvieron registros de la actividad eléctrica celular mediante microelectrodos. La ADO en concentraciones mayores de 10-8 M produce durante los dos primeros minutos un incremento súbito de la longitud del ciclo básico (LCB), de alrededor del 50 por ciento de su valor control, lo que después progresa hacia un estado estable. La curva dosis-respuesta en la fase estable es sigmoidal típica y semeja a las curvas de ocupación de receptores. Las pendientes del potencial de marcadores tienden a disminuir junto con la depresión de la LCB. Las oscilaciones post-potencial inducidas por tener de estimulación muestran que la pendiente de despolarización de la oscilación post-potencial disminuye con ADO 10-8 M pero no con concentraciones mayores. Los resultados encontrados sugieren que la ADO provoca un incremento en la corriente de potasio tiempo independiente. Este efecto parece depender de la estimulación de receptores específicos. El que la adenosina tenga un curso temporal bifásico sugiere la existencia de receptores purinérgicos con afinidades y constantes de disociación distinta pero con efectos similares y que podrían ser subtipos de receptores A1


Sujets)
Chiens , Animaux , Adénosine/analyse , Adénosine/biosynthèse , Stimulation électrique , Fonction ventriculaire , Fonction ventriculaire/physiologie , Techniques in vitro , Fibres de Purkinje/anatomie et histologie , Fibres de Purkinje/effets des médicaments et des substances chimiques , Fibres de Purkinje/physiologie , Ventricules cardiaques/physiologie
3.
Biol. Res ; 28(2): 165-71, 1995.
Article Dans Anglais | LILACS | ID: lil-228560

Résumé

The metabolites that mediate coronary reactive hyperemia have not been definitely identified. Although adenosine and endothelium derived substances seem to be involved, their relative contributions have not been defined yet. In the canine coronary circulation, we studied the relative participation of adenosine, nitric oxide and prostacyclin in reactive hyperemia, by measuring the changes produced by interfering with the synthesis or action of these metabolites. The dose-response curve for flow changes vs intracoronary administration of adenosine was displaced to the right after the inhibition of nitric oxide synthesis with N-omega-nitro-L-arginine, revealing that nitric oxide release partly mediates the vasodilator action of adenosine. The inhibition of PGI-2 synthesis with indomethacin did not modify reactive hyperemia. Interference with adenosine action, by administration of adenosine deaminase plus theophylline, decreased reactive hyperemia by 31.0 +/- 4.0 percent (p < 0.001). Inhibition of nitric oxide synthesis decreased reactive hyperemia by a larger (p < 0.005) magnitude, 41.0 +/- 3.9 percent (p < 0.001), revealing the existence of other stimuli for nitric oxide release in reactive hyperemia besides adenosine. Simultaneous inhibition of nitric oxide and PGI-2 syntheses and of adenosine action reduced reactive hyperemia, but the effect was not additive, reaching 49.5 +/- 4.5 percent of control. Since nitric oxide and adenosine are the most important mediators in reactive hyperemia so far described, our results suggest that other metabolites, acting directly or through mediators other than adenosine or nitric oxide, are responsible for about 50 percent of coronary reactive hyperemia


Sujets)
Animaux , Chiens , Adénosine/physiologie , Maladie coronarienne/physiopathologie , Endothélium vasculaire/physiopathologie , Hyperhémie/physiopathologie , Agents neuromédiateurs/physiologie , Monoxyde d'azote/physiologie , Adénosine/biosynthèse , Adénosine/sang , Antienzymes/pharmacologie , Prostacycline/pharmacologie , Monoxyde d'azote/biosynthèse , Monoxyde d'azote/sang , Nitroarginine/pharmacologie , Antiagrégants plaquettaires/pharmacologie
4.
Saudi Heart Journal. 1993; 4 (1): 89-98
Dans Anglais | IMEMR | ID: emr-30797

Résumé

Adenosine formation is augmented when the O2 supply is inadequate. Cardiac actions of adenosine can increase O2 supply [vasodilation] and decrease O2 consumption. We suggest that adenosine serves as a negative-feedback signal to correct an imbalance betweenO2 supply and consumption, thus acting as a cardioprotective metabolite


Sujets)
Adénosine/pharmacologie , Adénosine/métabolisme , Adénosine/biosynthèse
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