Changes of lymphatic vessel response to norepinephrine in hemorrhagic shock rats

AIM:To observe the changes of lymphatic vessel response to norepinephrine (NE) in hemorrhagic shock (HS) rats,and to explore the role of lymphatic reactivity in the pathogenesis of shock.METHODS:The lymphatic vessel pressure was observed through intubating into abdomen thoracic duct in 8 rats in sham group and HS group (which was bled from femoral artery until the mean arterial pressure to 40 mmHg).The changes of lymphatic vessel pressure response to NE at different time points were observed by injection of NE (5 μg/kg) through femoral vein.The spontaneous contraction frequency (F),maximal contraction diameter (a),maximal diastolic diameter (b) and static diameter (c) of mesenteric lymphatic (ML) living samples in 8 rats of each group were recorded through microcirculation video systems continuously.The changes of lymphatic fractional contraction index (index I),total contractile activity index (index II) and lymphatic dynamic index (LD-index) (to show the value using △F,△index I,△indexⅡ,△LD-index) were calculated after injection of NE at different time points.RESULTS:The changes of lymphatic boosting pressure response to NE in HS group was started to diminish 30 min after shock,and showed a progressive decreasing trend which significantly reduced than that in sham group at all time points of shock 1 h-3 h.In HS group,the △F,△indexⅡ,△LD-index at shock 1 h,the △F,△index I,△indexⅡ,△LD-index at shock 1.5 h and 2 h were significantly lower than those in sham group,and the △F,△index I,△indexⅡ,△LD-index at all time points were significantly decreased as compared to the values of pre-shock.CONCLUSION:Lymphatic vessel reactivity in shock rats is progressive declined in the process of hemorrhagic shock.The lymphatic vessel hypo-reactivity might play an important role in the pathogenesis of shock.