Crissinger K D, Kvietys P R, Granger D N
Department of Physiology and Biophysics, Louisiana State University Medical Center, Shreveport 71130-3932.
Am J Physiol. 1988 May;254(5 Pt 1):G658-63. doi: 10.1152/ajpgi.1988.254.5.G658.
The response to venous pressure elevation is an important criterion for determining whether metabolic or myogenic mechanisms are involved in local vasoregulation. We studied the effects of venous pressure elevation on intestinal hemodynamics and oxygenation in 20 mixed-breed piglets, divided equally among 1-day-, 3-day-, 2-wk-, and 1-mo-old animals. A venous circuit was established between the superior mesenteric and jugular veins, which allowed measurement of superior mesenteric blood flow, venous pressure, capillary pressure, and arteriovenous oxygen difference at venous pressures between 0 and 20 mmHg. The resting intestinal oxygen uptake in 1-day-old piglets was significantly higher than in 2-wk-old and 1-mo-old piglets. The vascular response to venous pressure elevation in 1-day-old piglets was characterized by reductions in total and precapillary resistance and increased oxygen uptake, while older animals responded to venous pressure elevation with increases in total and precapillary vascular resistance and reductions in oxygen uptake. These results indicate that metabolic factors exert a dominant influence on the intestinal vasculature of the newborn, while myogenic factors predominate in older animals in response to venous pressure elevation.
对静脉压升高的反应是确定代谢或肌源性机制是否参与局部血管调节的重要标准。我们研究了静脉压升高对20只杂种仔猪肠道血流动力学和氧合的影响，这些仔猪平均分为1日龄、3日龄、2周龄和1月龄组。在肠系膜上静脉和颈静脉之间建立了一个静脉回路，可测量肠系膜上静脉血流、静脉压、毛细血管压以及静脉压在0至20 mmHg之间时的动静脉氧差。1日龄仔猪静息时的肠道氧摄取显著高于2周龄和1月龄仔猪。1日龄仔猪对静脉压升高的血管反应表现为总阻力和毛细血管前阻力降低以及氧摄取增加，而年龄较大的动物对静脉压升高的反应是总血管阻力和毛细血管前血管阻力增加以及氧摄取减少。这些结果表明，代谢因素对新生仔猪的肠道血管系统起主要影响，而在年龄较大的动物中，肌源性因素在对静脉压升高的反应中占主导地位。
