The changes in the mRNA levels of calcium regulatory proteins in ischemia/reperfusion rat ventricles / 中国应用生理学杂志

<p><b>AIM</b>To investigate the changes in the expression of four kinds of calcium regulatory proteins mRNA on the isolated ischemia/ reperfusion (IR) hearts.</p><p><b>METHODS</b>The rat hearts were divided into two groups: control group and IR group which received 45 min exposure to Krebs-Henseleit solution after 15 min zero-flow global ischemia. The indexes of left ventricular function, such as LVDP, +dp/dt(max), -dp/dt(max), and an arrhythmia scoring system were compared between the two groups. The messenger ribonucleic acid (mRNA) amount of sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA), phospholamban (PLB), inositol 1,4,5-trisphosphate receptor2 (IP3R2) and ryanodine receptor2 (RyR2) was measured by reverse transcription-polymerase chain reaction (RT-PCR) and normalized to the mRNA levels of beta-actin.</p><p><b>RESULTS</b>In the IR group, LVDP, +dp/dt(max) and -dp/dt(min) of the isolated hearts were depressed and the high rate of arrhythmias occurred during reperfusion. The levels of SERCA, IP3R2, RyR2 mRNA were lower in the IR isolated hearts group than those in the control group, while there was no difference in the level of phospholamban.</p><p><b>CONCLUSION</b>These data suggest that myocardial ischemia/reperfusion can induce the depression of cardiac performance and an increased risk of arrhythmias, concomitant with the decrease in SERCA, IP3R2, RyR2 mRNA steady state levels.</p>

Relaxant effect of Astragalus membranaceus on smooth muscle cells of rat thoracic aorta / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effect of Astragalus membranaceus(AM) on vascular circles and the underlying mechanisms.</p><p><b>METHODS</b>The study was performed with the model of isolate rat thoracic aorta rings in organ bath. When the endothelium of rat thoracic aorta was removed,the effect of accumulated AM on aorta rings in resting tension, or pre-constricted with KCl, or pre-constricted with phenylephrine (PE) was observed. And to explove the mechanism, the aorta rings were incubated with Ca(2+)-free medium alone, or Ca(2+)-free medium plus heparin, or propranolol alone before pre-contraction with PE.</p><p><b>RESULTS</b>AM had no significant effects on aorta rings in resting tension or pre-constricted with KCl. When the concentration of AM was cumulated to 10(-1), 3 x 10(-1),10(0), 3 x 10(0) g/L, it caused concentration-dependent relaxation while aorta rings were pre-constricted with PE(3 x 10(-7)mol/L), compared with the control [(90.4 +/-4.2)% compared with (94.7 +/-2.4)%,(86.1 +/-5.0)% compared with (92.6 +/-3.2)%, (82.3 +/-5.9)% compared with (90.4 +/-3.6) %, (78.3 +/-6.0)% compared with (88.1 +/-4.0)%]. This effect was not inhibited by Ca(2+)-free medium or propranolol alone. However, the effect was attenuated by the co-incubation with heparin and Ca(2+)-free medium [without heparin:(76.2+/-4.3)% compared with (92.3 +/-5.9)%, with heparin: (95.3+/-0.5)% compared with (95.1+/-0.6)%].</p><p><b>CONCLUSION</b>The results indicate that AM can relax the rat thoracic aorta rings without endothelium. The mechanism may include the inhibition of intracellular calcium ions release by the 1,4,5-triphosphate inositol-receptor-dependent pathway in vascular smooth muscle cells.</p>