Effect of chronic intermittent hypobaric hypoxia on relaxation of aorta and mechanisms in developing rats / 中国药理学通报

Aim To investigate the effect of chronic intermittent hypobaric hypoxia (CIHH) on relaxation of thoracic aorta rings in male developing rats and the underlying mechanisms. Methods Male neonatal Spra-gue-Dawlay ( SD) rats were randomly divided into eight groups respectively: CIHH treatment group (CIHH), group of one-week post-CIHH (CIHH-pl), group of two-week post-CIHH ( CIHH-p2 ) , group of three-week post-CIHH (CIHH-p3 ) , control group for CIHH (Con), control group for CIHH-pl (Con-1), control group for CIHH-p2 ( Con-2) and control group for CIHH-p3 (Con-3 ). Rats in CIHH groups were put into a hypobaric chamber with the mother rats 1 ~ 3 days before the birth to get a hypobaric hypoxia exposure mimicking 3 km altitude for 42 days, 5 hours daily. Rats in control groups were kept in the same environment as CIHH rats except hypoxia exposure. After anaesthetized with pentobarbital sodium (50 mg • kg-1 i. p. ), the thorax of rats was opened and thoracic aorta rings were made. The artery rings were placed in the bath chamber filled with K-H solution, and the relaxation of artery rings was recorded under normoxia or a-cute hypoxia conditions, respectively. Results (1) Under normoxia condition, the acetylcholine ( ACh)-induced relaxation of thoracic aorta increased obviously in CIHH groups compared with corresponding Con groups ( P < 0. 05 ). ( 2 ) The enhancing effect of CIHH treatment on thoracic aorta could be maintained for at least three weeks (P < 0. 05). (3 ) Under acute hypoxia condition, ACh-induced relaxation of thoracic aorta in each group decreased obviously, but the decrease in CIHH groups was significant less than that in Con groups ( P < 0.05 ). (4) The enhancement of CIHH on relaxation of thoracic aorta could be reversed by indomethacin (Indo), a cyclooxygenase inhibitor, glibenclamide (Gli), a KATP blocker, and Tempo, a free radical scavenger. Conclusions CIHH augments endothelium-dependent relaxation in thoracic aorta of developing rats. Also, CIHH can antagonize the inhibition of acute hypoxia on relaxation of thoracic aorta. The enhancing effect of CIHH treatment may be related with the increase of prostacyclin, the opening of KATP and free radical production.

Vasorelaxation effect of gastrodin on isolated thoracic aorta rings of rats / 中国结合医学杂志

<p><b>OBJECTIVE</b>To study the effect of gastrodin on isolated thoracic aorta rings of rats and to investigate the potential mechanism.</p><p><b>METHODS</b>A perfusion model of isolated thoracic aorta rings of rats was applied. The effect of cumulative gastrodin (5, 50, 100,150, 200, and 250 μmol/L) on endothelium-intact aorta rings was investigated. The same procedure was applied to observe the effect of gastrodin on endothelium-intact/denuded aorta rings pre-contracted with 10(-6) mol/L phenylephrine hydrochloride (PE). The aorta rings incubated by 200 mmol/L gastrodin in the Ca(2+)-free (K-H) solution was contracted by using PE. The effect of 200 mmol/L gastrodin on endothelium-denuded aorta rings pre-contracted with 60 mmol/L KCl was also observed.</p><p><b>RESULTS</b>Compared with the denuded gastrodin group, the intact gastrodin group could significantly relax the PE-contracted aorta rings (P<0.01). In Ca(2+)-free (K-H) solution KHS, the PE-induced contraction rate of aorta rings pre-incubated by gastrodin was 6.5%±0.7%, which was significantly less than the control group (11.8%±0.9%,P<0.01). However, after 3 mmol/L CaCl2 was added, the Ca(2+)-induced contraction in the gastrodin group (51.7%±2.4%) was similar to that in the control group (49.8%±2.8%). The contractile rate of rings in the KCl-contracted gastrodin group (96.3%±0.6%) was not significantly different from that in the control group (96.8%±1.2%).</p><p><b>CONCLUSIONS</b>Gastrodin has the effect of vasorelaxation on isolated thoracic aorta rings of rats. The mechanism of the vasorelaxation of gastrodin may mainly work through the inhibition of inositol 1, 4, 5-trisphosphosphate receptor on the sarcoplasmic reticulum of the arterial smooth muscle, which leads to the reduction of the Ca(2+) released from the sarcoplasmic reticulum.</p>

Relaxant effects of total flavonoids of buckwheat flowers and leaves on rat thoracic aorta and underlying mechanisms / 中国药理学通报

Aim To explore the vasodilative effect on rat thoracic aortic ring of total flavonoids of Buckwheat flowers and leaves(TFBFL) and the underlying mechanisms.Methods Isometric tension measurements were used to study the effect of TFBFL on isolated rat thoracic aorta rings.Laser scanning confocal microscope was employed to measure the concentration of intracellular free calciums.Results In aorta rings precontracted with phenylephrine or potassium chloride,TFBFL caused a dose-dependent relaxation in both endothelium-intact and denuded rings and the relaxant effect of TFBFL was more potent on endothelium-intact aorta rings than that on endotheliumdenuded aorta rings(P