Shoukas A A, Bohlen H G
Department of Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
Am J Physiol. 1990 Sep;259(3 Pt 2):H674-80. doi: 10.1152/ajpheart.1990.259.3.H674.
The hypothesis that the pressure-diameter relationship of intestinal venules in rats is primarily determined by sympathetic nervous system activity was tested. The pressure-diameter relationship of the smallest to largest diameter (20-100 microns) intestinal venules of the rat was measured at rest, during hemorrhage to increase sympathetic neural activity, and during saline volume expansion to decrease sympathetic activity. During hemorrhage, the diameter of all venules decreased approximately 10% at 10 mmHg venous pressure, and the slope of the pressure-diameter relationship increased approximately 50% above control. Blood volume expansion led to an approximately 10% increase in venule diameter at 10 mmHg and a 25% decrease in slope. Denervation of the vessels causes concomitant vasodilation, which was greater than the vasodilation caused by blood volume expansion. Hemorrhage after denervation caused no significant changes in the relationship when compared with denervated control. Nitroprusside caused an even greater vasodilation when compared with the pressure-diameter relationship after denervation. The results suggest that the slope and 10-mmHg intercept of the pressure-diameter relationship for the largest through smallest intestinal venules and, therefore, their vascular compliance and capacitance characteristics are primarily determined by sympathetic activity.
对大鼠小肠小静脉压力-直径关系主要由交感神经系统活动决定这一假说进行了检验。在静息状态下、出血以增加交感神经活动期间以及生理盐水扩容以降低交感神经活动期间，测量了大鼠直径从最小到最大（20 - 100微米）的小肠小静脉的压力-直径关系。在出血期间，所有小静脉的直径在静脉压为10 mmHg时大约减小10%，压力-直径关系的斜率比对照增加约50%。血容量扩充导致在10 mmHg时小静脉直径增加约10%，斜率降低25%。去神经支配血管会伴随血管舒张，其程度大于血容量扩充引起的血管舒张。与去神经支配对照相比，去神经支配后出血对该关系未造成显著变化。与去神经支配后的压力-直径关系相比，硝普钠引起的血管舒张甚至更大。结果表明，从最大到最小的小肠小静脉压力-直径关系的斜率和10 mmHg截距，以及因此它们的血管顺应性和容量特性主要由交感神经活动决定。
