Changes in the blood supply of the gastrointestinal tract in rats with age.

Regional blood flow of the gastrointestinal (GI) tract and cardiac output have been determined in male Sprague-Dawley rats weighing from 30-726 g. The cardiac output (ml/min per kg) was highest in rats weighing 80-100 g. In heavier rats the cardiac output decreased proportionally with the body weight. The gradient of blood flow to the different parts of the GI tract develops step by step. In the weaning period the blood flow (ml/min per g tissue) through the stomach was less than that through the distal parts of the GI tract. However, the blood flow through the small intestine, cecum and large intestine was uniform at this age. In rats weighing 80-100 g the blood flow through both the cecum and large intestine was less than that through the small intestine. The gradient in blood flow through the various segments of small intestine developed last.