The Change Of Circulation Pressure In Septic Shock And The Role Of Muscarinic Receptor In Vascular Ex Vivo During Endotoxin

Objective1. To investigate the change of pulmonary arterial pressure (PAP ),pulmonary venous pressure (PVP) and systemic arterial pressure (SAP) during endotoxin shock .2. Research the role of LPS and M receptor to circulus vasculosus ex vivo during endotoxin shock.Materials and methodsAnimalsPrimary part: Male, health, adult dog 14, are all provided by Chinese medicine university experimental animal department.Second part: Male, health, albino rabbit 6, are all provided by Chinese medicine university experimental animal department.Agents and EquipmentsAgents: lipopolysaccharide are bought from the sigma company(pattern number L2880);Aritox are bought from the Hefeng company, pattern number 0609051; Lactated Ringer'S Solution are bought from the Dazhong company ,pattern number 7F704; pentobarbital sodium are bought from the Tairi company; normal saline are bought from the Baite company, pattern number C0701121A; Darifenacin are bought from the sigma company; phenylephrine are bought from the Wlande company; acetylcholine are bought from the sigma company;KRB;RPMI-1640 are bought from the Jiancheng company.Equipments: siemens 900C breathing machine (germany);preesure capsule (Japan); electrophysiolograph, circulus vasculosus fitting, thermostatic waterbath are bought from the Chengdu equipment factory. MethodsIn vivo: 14 healthy adult male mongrel canine were randomly divided into 2 groups: Normal Saline group (NS 1ml/kg,n = 7); LPS group(LPS 1mg/kg,n=7). Catheters were placed in femoral arteries , pulmonary arteries and prlmonary vein in each canine after to anesthetize in order to monitor the change of systemic arterial pressure(SP) ,pulmonary artery pressure(PAP) and prlmonary venous pressure(PVP).Ex vivo: 6 albino rabbits heart was arrested with gas embolism. The heart and lungs were removed from the thorax en bloc, and the pulmonary artery and aorta pectoralis were dissected free. Aorta pectoralis (2-3mm inner diameter ) and PA (1-2 mm inner diameter ID) were carefully dissected. Observation the role of LPS and M receptor blocking pharmacon darifenacin in the rings by tension transducerResult assessmentIn vivo: The animal blood pressure breakdown after inject LPS,the amplitude exceed 40% which confirms the animal appearanced endotoxin shock.Ex vivo: Vascular rings were vertically mounted between two stainless steel hooks in organ baths filled with 5 ml of KRB solution (37℃) gassed with 95% 02 and 5% CO2. After the vascular rings had been stretched to their optimal resting tension, the contractile response to 60 mM phenylephrine was assessed. we can think vascular take when its construction argument come to 300mg .The result of contractile response can express by g.tension/mg.dw, Relaxation responses to ACh in the ring studies are expressed as the percentage contraction induced by PE (1μmol/L) .Data analysisStatistical analyses are performed with SPSS13.0 software. All data are expressed as means±SD.The analysis are performed with T-test, P value of <0.05 is accepted as statistically significantResultIn vivo: (1) The change of pressure of circulation: the SP, PAP and PVP is no statistical significance compared with NS group. There is a little decrease in LPS.(2) The change of SP: compared with NS group, SP decreased quickly at the second minute after endotoxin in LPS group, The SP begins to decrease after intravenous LPS in LPS group which is from 132.9±9.42 mmHg to 40.91±4.36mmHg. The decreased amplitude is 70% of the base value.(3) In order to better compare the systemic circulation and pulmonary circulation changes in different, We compare the N group and L group PAP / SP ratio, results showed that after intravenous injection of LPS, this ratio was significantly increased, indicating systemic blood pressure compared to the sharp decline in the relative performance of pulmonary circulation to high pressure.Ex vivo:(1)The tension of pulmonary artery and aortic is 3.34±0.91 and 5.85±1.37, after intravenous LPS in LPS group which is changed to 3.00±0.90 and 4.29±1.30, P<0.05. (2) The experimental results compared to N group and L group after LPS incubation of pulmonary artery and the ratio of aortic contractile response showed aorta after incubation with LPS, decreased contractile response of the more obvious, and the decrease in pulmonary less than the thoracic aorta, so the ratio of L group is higher than N group.(3)The relaxation response of pulmonary artery in NS group is 77.43±5.76 then change to 25.43±3.09 after treatment by M receptor blocking pharmacon darifenacin,the arteriae aorta is 75.11±4.99 to 15.35±3.22, P<0.05. The tension of pulmonary artery in LPS group is 45.52±2.41 then change to 20.56±3.03 after treatment by M receptor blocking pharmacon darifenacin,the arteriae aorta is 42.21±2.56 to 14.32±2.51, P<0.05.Conclusion1. Intravenous Escherichia coli endotoxin 1mg/kg can construct a successful canine model of septic shock.2. Endotoxin group blood pressure sharp decline, pulmonary circulation is far less than that, so the relative increase in performance3. With the corresponding in vivo, the aorta, pulmonary blood vessels were incubated with LPS, the contraction rate of decline, a decrease in pulmonary vascular aorta is less than aorta4. M receptor in endothelial activation role can produce vasodilation, when incubated with LPS after endothelial damage, weakening or disappearance of diastolic function.