RÉSUMÉ
Beta-adrenergic receptor (βAR)-dependent blood vessel relaxation is impaired in older animals and G protein activation has been suggested as the causative mechanism. Here, we investigated the role of βAR subtypes (β1AR, β2AR, and β3AR) and cAMP in maturation-dependent vasorelaxation impairment. Aortic rings from 15 Sprague-Dawley male rats (3 or 9 weeks old) were harvested and left intact or denuded of the endothelium. Vascular relaxation in aortic rings from younger and older groups was compared in the presence of βAR subtype agonists and antagonists along with cAMP and cGMP antagonists. Isolated aortic rings were used to evaluate relaxation responses, protein expression was evaluated by western blot or real time PCR, and metabolites were measured by ELISA. Expression of βAR subtypes and adenylyl cyclase was assessed, and cAMP activity was measured in vascular tissue from both groups. Isoproterenol- and BRL744-dependent relaxation in aortic rings with and without endothelium from 9-week-old rats was impaired compared with younger rats. The β1AR antagonist CGP20712A (10-7 M) did not affect isoproterenol or BRL744-dependent relaxation in arteries from either group. The β2AR antagonist ICI-118,551 (10-7 M) inhibited isoproterenol-dependent aortic relaxation in both groups. The β3AR antagonist SR59230A (10-7 M) inhibited isoproterenol- and BRL744-dependent aortic ring relaxation in younger but not in older rats. All βAR subtypes were expressed in both groups, although β3AR expression was lower in the older group. Adenylyl cyclase (SQ 22536) or protein kinase A (H89) inhibitors prevented isoproterenol-induced relaxation in younger but not in older rats. Production of cAMP was reduced in the older group. Adenylyl cyclase III and RyR3 protein expression was higher in the younger group. In conclusion, altered expression of β3AR and adenylyl cyclase III may be responsible for reduced cAMP production in the older group.
Sujet(s)
Animaux , Mâle , Aorte thoracique/effets des médicaments et des substances chimiques , Aorte thoracique/physiopathologie , Vasodilatation/effets des médicaments et des substances chimiques , Vasodilatation/physiologie , Antagonistes des récepteurs bêta-1 adrénergiques/pharmacologie , Inhibiteurs des adénylate cyclases/pharmacologie , Aorte thoracique/physiologie , Facteurs temps , Expression des gènes , Adenylate Cyclase/physiologie , Technique de Western , Facteurs âges , AMP cyclique/analyse , AMP cyclique/métabolisme , Salbutamol/pharmacologie , Dobutamine/pharmacologieRÉSUMÉ
AIM: To observe the changes of adengl cyclase(AC) and phosphodiesterase(PDE) activities of at different time point in hypothalamus of rats with fever and hypothermia. METHODS: Radioisotope method was used to measure the activity of AC and PDE. RESULTS:The fresh yeast caused rats fever after subcutaneous injection 4h( P
RÉSUMÉ
The effects of morphine, pethidine and fentanyl on adenyl cyclase (AC) and phospho- diesterases (PDE) in rabbit bronchial smooth muscle were examined in vitro. The results were as follows: morphine could inhibit the activity of AC which was decreased from 15. 9911 ? 0. 8597u to 15.0463?0. 7989u, P
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Object To investigate the effects of Panax notoginseng saponins (PNS) on myocardial Gs? mRNA expression of seriously scalded rat. Methods A 30% skin full thickness scald model was produced by immersing rat in 95 ℃ water for 10 s. The effects of PNS on myocardial Gs? mRNA level were observed with dot blotting hybridization and in situ hybridization technique; effects on cAMP and adenyl cyclase (AC) activities were determined with radioimmunoassay. Results Myocardial Gs? mRNA, AC activity and cAMP content were reduced significantly 3 h after scalding. PNS (100, 200 mg/kg) could markedly increase the level of myocardial Gs? mRNA expression. The elevated quantity was correlated markedly with PNS dosage (r = 0.95, P
RÉSUMÉ
24 white big ear female rabbits were divided into 3 groups at random, i. e. control group (CG), fever group (FG) and electric acupuncture group (EAG). CG were not given any treatment. Endotonin (ET) was i. v. injected into animals of FG and fever ensued. 80 min after the injection ET the body temperature of the animals raised 1.18℃. 80 min after the ET injection into animals of EAG. the body temperature of animals raise 0.35℃. The body temperature of CG was compared with that of FG an obvious difference (P
RÉSUMÉ
AIM: To observe the changes of AC activity and content of cAMP at different time point in hypothalamus of rats with fever and hypothermia. METHODS: Radioisotope method was used to measure the enzymatic activity of AC and the content of cAMP. RESULTS:(1)The fresh yeast caused fever after making model 4 h( P
RÉSUMÉ
Fourty rats were divided into four groups and the aseptic inflammation was induced by subcutaneous injection of cronton oil into the back of 30 rats. Body temperature were gradually rose up after injection. The highest temperature appeared on the second day, then run down in the following days, and went back to normal on the eighth day. Brain were dissected in 10 normal rats without fever(group 1), other 10 rats at the peak of fever(group 2), and another 10 rats in the recovery phase on the third day (group 3). Ten rats in group 4 were used for observing the whole process of temperature change from injection day to the eighth day without brain dissection. The results showed that at the peak of fever, the levels of both cAMP and AC activities in hypo. thalamus were increased (P