Portal Venous and Aortic Glucose and Lactate Changes in a Chronically Catheterized Rat

Abstract

ABSTRACI'. A method for portal venous, aortic, and gastric cannulation in the rat is described. Changes in mean portal venous and aortic blood glucose and lactate concentrations after an intragastric infusion of d-glucose to chronically catheterized rats (after regaining preoperative weight) were compared to those of acutely catheterized rats (1 h after catheter placement). Both portal venous and aortic catheters were patent for blood sampling in 67% of rats 8 days after catheter placement and 42% after 14 days. After intragastric infusion of 10 ml of 0.29 M dextrose, mean aortic blood glucose and lactate concentrations in chronically catheterized rats increased 80 and 73%, respectively, 15 min after infusion and decreased to preinfusion concentrations by 60 min. In acutely catheterized rats, mean aortic glucose and lactate concentrations increased linearly for 60 min. The concentration differences between portal venous and aortic blood glucose and lactate concentrations in chronically catheterized rats were not significantly different than baseline differences. The portal venous glucose concentrations were significantly greater than aortic concentrations in acutely catheterized rats 15, 30, and 45 min after the glucose infusion when compared to baseline differences. These data suggest that the rate of glucose uptake and metabolism to lactate is significantly altered in acutely catheterized rats when compared to chronically catheterized animals. (Pediatr Res 23: 235-240,1988) Abbreviation AVC, area under the curve.(4); manual manipulation of the bowel can alter mesenteric blood flow and anesthesia can alter mesenteric blood flow and intestinal perfusion (5). These factors can alter intestinal perfusion and oxygen delivery. In contrast, studies that use the technique of chronic catheterization avoid these artifacts (6).We have developed a rat model in which the portal vein, aorta, and stomach are catheterized chronically. Using this preparation, we serially determined in vivo portal venous and aortic blood concentrations of glucose, lactate, and alanine after a bolus intragastric infusion of glucose in nonstressed animals. We also determined the effects of surgery and anesthesia on portal venous and aortic blood glucose, lactate, and alanine concentrations. MATERIALS AND METHODS Animals.All experiments were performed in vivo using adult male albino Sprague-Dawley rats (200-300 g body weight). These animals were obtained from Simonsen Labs (Gilroy, CA) and allowed free access to water and rat food.Catheters. The portal vein catheter consisted of two 1.5 cm segments of PE 60 tubing (Clay Adams, Parsippany, NJ; ID 0.76 mm, OD 1.22 mm) connected to the ends of a 4.5-cm silastic tube (Dow Corning, Midland, MI; silastic ID 0.64 mm, OD 1.19 mm). The silastic tubing was stretched securely over the segment of PE 60 tubing. The ends of the PE 60 tubing were cut to a sharp point at an angle of approximately 45". The catheter was then placed over an 8.89-cm 25-gauge spinal needle (Becton Dickinson, Rutherford, NJ) which s...

Active transport of 3-O-methyl-glucose by the small intestine in chronically catheterized rats.

“…We speculate that the explanation for the lower fraction of active transport in those studies that conflict with our results is the adverse effects of surgical bowel manipulation and anesthesia on intestinal transport. In previous studies in rats by Kimura et al., there was a faster rate of increase in portal venous and aortic blood concentrations of glucose after a gastric infusion of glucose under chronic conditions in comparison with measurements immediately postoperative (28). In the accompanying paper, we show that active transport of glucose by the intestine is decreased 90% immediately after laparotomy while passive absorption remains unaffected (32).…”

“…The surgical procedure was performed under sterile conditions as previously described (28). Briefly, male Sprague-Dawley rats were anesthetized with ketamine 60 mg/kg and xylazine 1.0 mg/kg IM.…”

“…Therefore, it may not be appropriate to extrapolate the results obtained under these conditions to unanesthetized, nonlaparotomized animals (27). Using a chronically catheterized rat model, we showed that portal venous and aortic blood concentrations of glucose after a gastric bolus increased at a slower rate immediately postoperatively compared to subsequent measurements (28).…”

The effect of surgical bowel manipulation and anesthesia on intestinal glucose absorption in rats.

“…Kimura et al showed that portal venous and aortic blood concentrations of glucose and lactate after an intragastric bolus of glucose increased at a slower rate immediately postoperative compared to subsequent measurements (24). Singh et al showed decreased D-xylose absorption for 48 h after laparotomy in rats and concluded that measurements of gut absorptive capacity should be performed at least 3 d after laparotomy (25).…”

The Effect of Fasting on Rat Portal Venous and Aortic Blood Glucose, Lactate, Alanine, and Glutamine

“…Using aseptic technique, portal venous C02 after infusions of lactate (3). These important intestinal and aortic catheters were surgically placed as described previously metabolic functions release gluconeogenic precursors, alanine (12). After surgery, animals were weighed daily and the catheters and lactate, into the portal venous effluent which perfuses the were flushed with 0.35 ml of normal saline containing 500 U/ liver.…”