ABSTRACT
<p><b>OBJECTIVE</b>To observe the change of lymphatic reactivity to substance P (SP) during the process of hemorrhagic shock (HS) with a technique of lymphatic perfusion in vitro in this study.</p><p><b>METHODS</b>Male Wistar rats were randomly divided into control group (surgical procedure only) and HS group (the rats in this group were further divided into five subgroups: shock 0 h, 0.5 h, 1 h, 2 h and 3 h groups after duplicating the HS model with method of bloodletting to mean arterial blood pressure was 40 mmHg through the femoral venous). Thoracic ducts were separated from HS rats at the corresponding time points in each group. A segment of thoracic duct was pressed and perfused in vitro at transmural pressure of 3 cm H2O, and then stimulated with gradient SP respectively. The end systolic diameter, end diastolic diameter, contraction frequency (CF) and passive diameter of isolated lymphatics were measured, while the contraction amplitude (CA), tonic index (TI) and fractional pump flow (FPF) were calculated, and the different values between pre- and post- administration of SP of CF, CA, TI and FPF were calculated and expressed as Delta CF, Delta TI, Delta CA and Delta FPF to further assess the reactivity of lymphatics.</p><p><b>RESULTS</b>After SP incubation, the Delta CF, Delta TI, Delta CA and Delta FPF of 0 h- and 0.5 h shocked lymphatics were significantly increased when compared with that of control group on one or several concentrations. The Delta CF (at 3 x 10(-7) mol/L of SP) and Delta TI (1 x 10(-7) mol/L) of 2 h- shocked lymphatics and the Delta CF (1 x 10(-7) mol/L, 3 x 10(-7) mol/L), Delta TI (1 x 10(-7) mol/L) and Delta CA (1 x 10(-7) mol/L) of 3 h- shocked lymphatics were all significantly reduced when compared with control group.</p><p><b>CONCLUSION</b>The reactivity of lymphatics to SP presented a biphasic change during the process of HS: increase in early phase and decline in later stage.</p>
Subject(s)
Animals , Male , Rats , Lymphatic Vessels , Rats, Wistar , Shock, Hemorrhagic , Substance P , Thoracic DuctABSTRACT
The aim of the present study was to investigate the changes of lymphatic contraction after hemorrhagic shock in vitro and the underlying role of nitric oxide (NO). Rat thoracic duct segments were isolated at 0, 0.5, 1, 2 and 3 h after hemorrhagic shock. Using Pressure Myograph System, we determined contraction frequency (CF), end systolic diameter (ESD), end diastolic diameter (EDD) and passive diameter (PD) of isolated rat lymphatics under different transmural pressures (1, 3, 5, 7 and 9 cmH(2)O), then calculated contraction amplitude (CA), tonic index (TI) and fractional pump flow (FPF) of lymphatics. The results showed that in several transmural pressures, lymphatic CF, TI and FPF were significantly higher in shock 0 h and shock 0.5 h groups than those in control group (sham operation group). With the development of shock, lymphatic CF, TI and FPF decreased significantly in shock 2 h and shock 3 h groups compared with those in control group. We further discovered the role of NO in the changes of lymphatic contraction after hemorrhagic shock. Under 3 cmH(2)O transmural pressure, the changes of lymphatic contraction in shock 0.5 h and shock 2 h groups were analyzed following the incubation with several NO-related drugs alone or in combination. And the results showed that NO donor L-Arg reduced CF, TI and FPF in shock 0.5 h group to the control levels, while soluble guanylate cyclase inhibitor ODQ suppressed the effect of L-Arg. Moreover, NOS inhibitor L-NAME elevated the CF, TI and FPF of 2 h shock lymphatics to the control levels, while phosphodiesterase inhibitor aminophylline (AP) suppressed the effect of L-NAME. These results suggest that the lymphatic contractile activity exhibits a biphasic change during hemorrhagic shock, increasing in early phase and declining in later stage. And NO plays a major regulating role in the biphasic change of lymphatic contraction in hemorrhagic shock rats via cGMP pathway.