Traits characterizing those proteas adapted for polhnation by nonflying mammals include: bowlshaped heads bearing fleshy bracts, these borne on short, flexible peduncles, often at or near ground level (geoflorous) and hidden beneath dense overlying foliage (cryptic), and producing copious nectar (ca. 1.8 ml/head, standing crop); individual florets with wir>', yet flexible styles and a nectar-stigma distance of 10 mm; a distinctive yeastlike odor; nocturnal anthesis; sucrose-rich nectar with a high total carbohydrate content (ca. 36%) and a relatively low proportion of amino acids. Evidence of small-mammal visitation to protea flowering heads includes: the presence of pollen on the rostra (carried in a position to effect pollination when foraging for nectar); the transport of fluorescing powders to flowering heads both within and between plants; the accumulation of small-mammal feces in flowering heads, and the destruction of exciosure bags containing nectar-rich heads. The period of greatest small-mammal activity (1800 hr.) coincides with maximum flower opening. T maze experiments showed that small mammals, when given a choice between typically bird-pollinated proteas and those having characteristics of flowers pollinated by nonflying mammals, always foraged on the latter. That small mammals can effect pollination is indicated by their foraging behavior on flowering heads while in captivity, the morphological "fit" between individual florets and the rostra of small mammals, and by selective exciosure experiments that reduced seed set (50% and 95%) when small mammals were excluded and visitation was limited to insects (mostly honey bees). The nectar produced ' The study was supported in part by NSF grant (DEB 78-11624). We thank B.

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...

We compared the risk of intracranial hemorrhage after a hypovolemic, hypotensive insult followed by rapid volume replacement in three groups of beagle puppies: one group less than 12 h old, a second, 72 h of age, and a third, 72 h of age, which had been treated from birth with ovine prolactin in the dose per kilogram which prevents postnatal brain water loss in rabbits. Intracerebral hemorrhage occurred in 14% of day 1 animals, 68% of untreated animals on day 3, and 15% of the group treated with prolactin. These data suggest that postnatal loss of brain water predisposes to intracerebral hemorrhage and that treatment to prevent this water loss can reduce the risk of intracerebral hemorrhage at 72 h of age.

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these data suggest that the small intestine may be a significant source of lactate and alanine for utilization by the liver. During fasting, intestinal glutamine oxidation to C02 and the subsequent production of alanine are not affected (3, 9) and so the intestine may be an important source of alanine. These studies, which identified significant aerobic small intestinal metabolism of glucose to lactate and the oxidation of glutamine to C02 (1-4), were done under anesthesia and with bowel manipulation. Anesthesia can alter blood substrate concentrations as well as the metabolism of substrates (3). Ether, for example, increases blood glucose and lactate concentrations (10). Anesthesia also can decrease cardiac output which would decrease mesenteric blood flow and intestinal perfusion. Surgical manipulation can alter intestinal metabolism and perfusion. Metabolic studies involving the fetal lamb exemplify the importance of chronic catheterization in contrast to acute catheterization (1 1).We set out to determine the effect of fasting on small intestinal metabolism and the resulting effect on portal venous blood substrate concentrations under physiologic conditions. We used a chronically catheterized rat model in which the portal vein and aorta remained patent for blood sampling. The portal venous and aortic blood concentrations of glucose, lactate, alanine, and glutamine were measured in the fasted and fed states. In the fasting state intraluminal substrates are unavailable to the intestine, so the portal venous to aortic blood concentration gradient reflects qualitatively the utilization or production of blood borne substrates by the intestine. MATERIALS AND METHODS Animals.All experiments were performed in vivo using adult Many low birth weight infants are nourished using parenteral male, albino, Sprague-Dawley rats (200-300 g body weight). methods. If the intestine is primarily an absorptive organ, this These animals were obtained from Simonsen Labs (Gilroy, CA) therapy may be appropriate. However, the small intestine per-and allowed free access to water and rat food. The adult rats forms several major metabolic functions including oxidation of were weighed and anesthetized with a 20 mg/kg ketamine inglucose to lactate under aerobic conditions (1-3), oxidation of jected intramuscularly followed by a 10 mg/kg pentobarbital glutamine to C02 (3,4), and conversion of lactate to alanine and injected intrapentoneally. 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. Ramesy et al. (5) have reported elevated portal venous ml heparin and 2.5 mg/ml of ampicillin. concentrations of glucose, alanine, and lactate in fed rats. KatzThe effect offasting ...