Search results for "RATS"
showing 10 items of 3537 documents
Influence of cyclization and acyl substitution on the inotropic effects of adenine nucleotides.
1973
This study was designed to further elucidate relevance and mechanism of the positive inotropic action of cyclic N6-2′-O-dibutyryl-AMP (DB-c-AMP). For this purpose the effects of cyclic N6-monobutyryl-AMP (N6-MB-c-AMP), noncyclic N6-2′-O-3′-O-tributyryl-5′-AMP (TB-AMP), c-AMP, adenosine and various adenine nucleotides (ATP, ADP, AMP) on myocardial contractile force (CF) were investigated and compared to that of DB-c-AMP. The experiments were performed on isolated, electrically driven (frequency 2 Hz) rat left auricles, i.e. on a preparation in which DB-c-AMP consistently produced positive inotropic effects. The following results were obtained: From the failure of non-cyclic TB-AMP to increas…
Differential electrophysiologic and inotropic effects of phenylephrine in atrial and ventricular heart muscle preparations from rats.
1991
Stimulation of alpha 1-adrenoceptors evokes a different pattern of inotropic responses in atrial and ventricular heart muscle preparations from rats. The inotropic effects are accompanied by different changes in membrane potential. In an attempt to clarify the question whether or to which extent these events are causally related, the effects of phenylephrine on force of contraction, transmembrane potential, Ca2+ current (ICa) and K+ currents were comparatively studied in either tissue. In atrial preparations, phenylephrine 10 mumol/l caused an increase in force of contraction, a marked prolongation of the action potential duration and a depolarization of the membrane at rest. In the ventric…
Papaverine enhances the negative inotropic effect of acetylcholine in rat auricles
1978
The negative inotropic effect of acetylcholine in rat left auricles is enhanced in the presence of the phosphodiesterase inhibitor papaverine. This result favours the idea of a cyclic GMP-mediated action of acetylcholine in the heart.
Cyclic AMP and cyclic GMP may play opposing roles in influencing force of contraction in mammalian myocardium.
1976
CYCLIC AMP and cyclic GMP have been suggested to play opposing regulatory roles in several biological systems1. Supporting evidence for the yin yang hypothesis of opposing biological regulation has been obtained in sympathetic ganglia2,3 and pyramidal neurones in the rat cerebral cortex4. In the mammalian heart, the role of cyclic AMP in mediating the positive inotropic response to catecholamines was advanced by the observation that the inotropic effect was preceded by an increase in cyclic AMP levels5. On the other hand, the levels of cyclic GMP were found to be increased after cholinergic stimulation6. In frog, oscillations of cyclic AMP7 and cyclic changes in the levels of cyclic AMP and…
Effect of DB-c-AMP on mechanical characteristics of ventricular and atrial preparations of several mammalian species
1974
Conflicting results exist about the influence of cyclic N6-2′-O-dibutyryl-AMP (DB-c-AMP) on myocardial contractile force. The present study was designed to examine whether the positive inotropic action of DB-c-AMP is restricted to certain model preparations or whether it can be assumed to represent a more general effect of the drug. Therefore, the effects of DB-c-AMP on myocardial force and on various parameters of the isometric contraction curve were examined in isolated electrically driven (0.5–2Hz) ventricular and atrial preparations of several mammalian species (cat, rabbit, calf, sheep, rat and guinea-pig). The following results were obtained:
Na+ dependent glutamate transporters (EAAT1, EAAT2, and EAAT3) in primary astrocyte cultures: effect of oxidative stress.
2001
Abstract The Na + -dependent l -glutamate transporters EAAT1(GLAST), EAAT2 (GLT-1) and EAAT3 (EAAC1) are expressed in primary astrocyte cultures, showing that the EAAT3 transporter is not neuron-specific. The presence of these three transporters was evaluated by RT–PCR, immunoblotting, immunocytochemical techniques, and transport activity. When primary astrocyte cultures were incubated with l -buthionine-( S , R )-sulfoximine (BSO), a selective inhibitor of γ-glutamylcysteine synthetase, the GSH concentration was significantly lower than in control cultures, but the expression and amount of protein of EAAT1, EAAT2 and EAAT3 and transport of l -glutamate was unchanged. Oxidative stress was c…
Lethal and behavioural effects of a green insecticide against an invasive polyphagous fruit fly pest and its safety to mammals
2021
Abstract Plant essential oil-based insecticides, with special reference to those that may be obtained from largely available biomasses, represent a valuable tool for Integrated Pest Management. However, the sublethal effects and the potential effects on aggressive insect traits of these green insecticides are understudied. Herein, the lethal and sub-lethal effects of the carlina oxide, constituting more than 97% of the whole Carlina acaulis (Asteraceae) root essential oil (EO), were determined against an invasive polyphagous tephritid pest, Ceratitis capitata (medfly). The carlina oxide was formulated in a mucilaginous solution containing carboxymethylcellulose sodium salt, sucrose, and hyd…
The Fibril-associated Collagen IX Provides a Novel Mechanism for Cell Adhesion to Cartilaginous Matrix
2004
Collagen IX is the prototype fibril-associated collagen with interruptions in triple helix. In human cartilage it covers collagen fibrils, but its putative cellular receptors have been unknown. The reverse transcription-PCR analysis of human fetal tissues suggested that based on their distribution all four collagen receptor integrins, namely alpha1beta1, alpha2beta1, alpha10beta1, and alpha11beta1, are possible receptors for collagen IX. Furthermore primary chondrocytes and chondrosarcoma cells express the four integrins simultaneously. Chondrosarcoma cells, as well as Chinese hamster ovary cells transfected to express alpha1beta1, alpha2beta1, or alpha10beta1 integrin as their only collage…
Prestress in the extracellular matrix sensitizes latent TGF-β1 for activation
2014
A mild strain induced by matrix remodeling mechanically primes latent TGF-β1 for its subsequent activation and release in response to contractile forces.
Preclinical immunomodulation by the probiotic Bifidobacterium breve M-16V in early life
2016
This study aimed to investigate the effect of supplementation with the probiotic Bifidobacterium breve M-16V on the maturation of the intestinal and circulating immune system during suckling. In order to achieve this purpose, neonatal Lewis rats were supplemented with the probiotic strain from the 6th to the 18th day of life. The animals were weighed during the study, and faecal samples were obtained and evaluated daily. On day 19, rats were euthanized and intestinal wash samples, mesenteric lymph node (MLN) cells, splenocytes and intraepithelial lymphocytes (IEL) were obtained. The probiotic supplementation in early life did not modify the growth curve and did not enhance the systemic immu…