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Evolution of portal hypertension and mechanisms involved in its maintenance in a rat model
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1985
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HypertensionUrologyOrgan PhysiologyGastrointestinal Peptide HormoneMedicineLiver PhysiologyPortal HypertensionPhysiologyGastroenterologyVascular PharmacologyBlood FlowVascular BiologyRenal PathophysiologyPortal VeinRat ModelAnesthesiologyHealth Sciences
The sequence of events leading to the circulatory disarray in portal hypertension remains unknown. The study evaluated the chronological chain of hemodynamic changes following portal hypertension induced by partial portal vein ligation. Using 45 portal‑hypertensive and 29 sham rats, the authors measured portal blood flow, resistance, and portal‑systemic shunting with radioactive microspheres to track the interaction between flow, resistance, and shunting over time. After partial ligation, portal vein constriction caused resistance‑induced hypertension with higher portal resistance, pressure, and reduced inflow, and the subsequent increase in portal venous inflow was identified as a key factor maintaining portal hypertension. Abstract truncated at 250 words.
In rats with portal hypertension induced by partial ligation of the portal vein, we have recently demonstrated an increased portal venous inflow that becomes an important factor in the maintenance of portal hypertension. The sequence of events that leads into this circulatory disarray is unknown. We evaluated chronologically the chain of hemodynamic changes that occurred after portal hypertension was induced by partial ligation of the portal vein. In this model it is possible to follow, from the initiation of the portal-hypertensive state, the interaction between blood flow and resistance in the portal system as well as the relation between the development of portal-systemic shunting and the elevated portal venous inflow. The study was performed in 45 portal-hypertensive rats and in 29 sham-operated rats. Blood flow and portal-systemic shunting were measured by radioactive microsphere techniques. The constriction of the portal vein was immediately followed by a resistance-induced portal hypertension characterized by increased portal resistance (9.78 +/- 0.89 vs. 4.18 +/- 0.71 dyn X s X cm-5 X 10(4), mean +/- SE, P less than 0.01), increased portal pressure (17.7 +/- 0.9 vs. 9.5 +/- 0.6 mmHg, P less than 0.001), and decreased portal venous inflow (3.93 +/- 0.26 vs. 6.82 +/- 0.49 ml X min-1 X 100 g body wt-1, P less than 0.001). (ABSTRACT TRUNCATED AT 250 WORDS)