| Objective: To investigate the cardiovascular benefits of Res from both aspects in vivo and vitro. The first part of the present study was to investigate the effects of Res on left ventricular function and blood pressure in rabbits;The second part of the present study was to investigate the effects of Res on spontaneous heart rate, contraction force and vasodilatation of artery in rabbits and their underlying mechanisms.Methods:Part 1 The effects of Res on left ventricular function and blood pressure in rabbits.To collect the indexes of Res derivatives on left ventricular function and SBP in rabbits through intubation into left ventricle and femoral artery with MS4000U-1C biological signal disposal system.Part 2 The effects of Res on spontaneous heart rate, contraction force and vasodilatation of artery in rabbits and their underlying mechanismsRabbit(2.0±2.5kg) was killed with a single blow on head, the heart and renal artery and common carotid artery were removed and placed in cold(04℃) oxygenated(95%O2 and 5%CO2) Krebs and K-R solution respectively. The region of the right atrium bounded by the crista terminalis and the superior and inferior vena cava, and the interatrial septum was dissected free from the adjacent tissue. One side of the preparation was fixed to organ baths(34.535.5℃) oxygenated(95%O2 and 5%CO2) Krebs solution and the another was linked with MS4000U-1C biological signal disposal system into the computer and record the data. Renal artery and common carotid artery were suspended in organ baths(37℃) oxygenated(95%O2 and 5%CO2) K-R solution, and were prepared into two groups: the endothelium group and the endothelium removal group. Two groups were induced by 30mmol/L KC1 to maximum, then respectively administered by 1×10-6, 3×10-6, 1×10-6, 3×10-5, 1×10-4, 3×10-4, 1×10-3mo1/L every five minutes, and the changes were observed in the absence and presence of different blocking agents and the underlying mechanisms were studied.Results:Part 1 The effects of Res on left ventricular function and blood pressure in rabbitsCompared with blank group, Res obviously decreased the HR, LVSP, lv+dp/dtmax, lv-dp/dtmax and SBP, and took on dose dependant in certain time. There is no significant difference in the LVDP, LVEDP and t-dp/dtmax.Part 2 The effects of Res on spontaneous heart rate, contraction force and vasodilatation of renal artery in rabbits and their underlying mechanismsRes showed a dose-dependent relaxant effect on renal artery at 10-610-3 mol/L. At the concentration of 10-3mol/L, the effect was attenuated by(18.2±2.3)% in the endothelium removal group, and it was significantly different from the control group. The effect was lowered by(14.7±2.7)% in L-NAME group and by(10.5±3.1)% in Gli group and by(11±1.9)% in MB group respectively, showing significant difference compared with the control groups. However, in the groups of TEA, 4-AP, BaCl2, Indo, Atr, Phe and Pro, the effect was not obviously different compared with the control group. Res also showed a relaxant effect on de-endothelium vessels, which was partly blocked by Gli. Res reduced the spontaneous heart rate, and as compared with Res group, spontaneous heart rate of Gli group was partly blocked, those of TEA, 4-AP, BaCl2, Atropine groups were not blocked. Res could not obviously inhibit contraction force.Conclusion:Part 1 The effects of Res on left ventricular function and blood pressure in rabbitsLVSP represent the maximal value of the pressure inside the left ventricles, LVSP descend when cardiac muscle contraction is weakened or fore-and-aft load is diminished. So far as, lv±dp/dtmax are thought adequate to evaluate cardiac muscle contraction function. When the dint factor function is changed, lv+dp/dtmax and t-dp/dtmax are contrary in variation direction. While the loading factor function is changed, lv+dp/dtmax and t-dp/dmax are in coincidence in variation direction. This experiment confirms that Res can weaken cardiac muscle contraction and reduce HR and SBP. Part 2 The effects of Res on spontaneous heart rate, contraction force and vasodilatation of artery in rabbits and their underlying mechanismsRes relaxes the renal artery both endothelium dependent and independent manner. In the endothelium-dependent manner, the mechanism of vasodilatation may be associated with NO system and KATP channel, while in the endothelium-independent manner, the mechanism of vasodilatation may be associated with KATP channel. Res reduces the spontaneous heart rate which mechanism of action may relate to the opening of KATP。Res can not obviously inhibit contraction force.
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