Effects of varying hematocrit on intestinal oxygen uptake in neonatal lambs

Holzman, Ian R.; Tabata, B.; Edelstone, Daniel I.

doi:10.1152/ajpgi.1985.248.4.g432

Cited by 8 publications

(7 citation statements)

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“…The effect of oil infusion on liver plasma flow in the present study was attributed to metabolizable energy (ME) intake during the blood sampling period or to neural or hormonal responses to postruminal oil infusion . While oil infusion decreased daily DMI in our study, the reduction occurred late in the day and before the morning milking, and thus feed DMI during the period of sampling was not affected (Holzman et al, 1985). In humans, increased splanchnic blood flow following ingestion of oil was accompanied by an increase in blood PCV, suggesting other factors are responsible for the increased flow observed (Brundin, 1998).…”

Section: Packed-cell Volume Blood Flow and Blood Gas Exchangecontrasting

confidence: 45%

Effects of Abomasal Vegetable Oil Infusion on Splanchnic Nutrient Metabolism in Lactating Dairy Cows

Benson¹,

Reynolds²,

Aikman

et al. 2002

Journal of Dairy Science

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Changes in the metabolism of nutrients by the portal-drained viscera (PDV) and liver may contribute to the reduction in dry matter intake (DMI) and other production responses generally observed in lactating dairy cows fed supplemental long-chain fatty acids (LCFA). In the present study, effects of a 7-d abomasal infusion of vegetable oil on arterial concentration and splanchnic (PDV and liver) metabolism of nutrients were measured in six cows at 55 (early lactation [ELAC]) and 111 (midlactation [MLAC]) d postpartum. Cows were fed for ad libitum DMI at 8-h intervals, and blood samples for measurement of splanchnic metabolism were obtained over 8 h beginning 2 h before feeding at 0830 h. Blood flow for the PDV and liver was increased by oil infusion and was greater in ELAC, despite similar-feed DMI during blood sampling. Increased blood flow in ELAC was associated with greater liver oxygen removal and glucose release that accompanied greater milk yield. In contrast, oil infusion had no effect on splanchnic oxygen use. Greater blood flow during oil infusion may have been due to specific effects of intestinal LCFA supply on PDV blood flow. Net PDV release and liver removal of branched-chain volatile fatty acids (VFA) and ammonia were increased by oil infusion. Net PDV release of longer-chain (4 and 5 C) VFA and NEFA was greater in ELAC, but net PDV flux of other nutrients was not affected by lactation stage, possibly due to the similarity of feed DMI. Oil infusion increased arterial concentration and net PDV release and liver removal of NEFA, and it decreased net liver release and arterial concentration of glucose. Effects of oil infusion on liver glucose release were associated with decreased daily DMI. In ELAC, arterial concentration and net liver removal of NEFA were also increased, but liver release of glucose was greater than in MLAC. Oil infusion and ELAC both increased net liver removal of L-lactate. The resulting decrease in net total splanchnic release of L-lactate in ELAC reflects decreased tissue energy balance of the cows. Generally, stage of lactation and relative milk yield had greater effects on metabolism of the liver than the PDV, in which metabolism was largely dictated by DMI. In the present study, there was little evidence to suggest an effect of stage of lactation on the metabolic response ofthe PDV and liver to postruminal LCFA supply.

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Section: Packed-cell Volume Blood Flow and Blood Gas Exchangecontrasting

confidence: 45%

Effects of Abomasal Vegetable Oil Infusion on Splanchnic Nutrient Metabolism in Lactating Dairy Cows

Benson¹,

Reynolds²,

Aikman

et al. 2002

Journal of Dairy Science

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“…These investigators did not compare nonfed and fed subjects at the same time on the first postnatal day, as was carried out here, although the substantial increase in baseline intestinal blood flow and oxygen uptake by postnatal day 3 and its decline by postnatal day 30 was first described by these workers (6)(7)(8)(9). It is clear that baseline hemodynamic and oxygenation parameters dramatically change during early postnatal life in swine, a process also noted in other species (11,16).…”

Section: Discussionmentioning

confidence: 86%

Developmental expression of eNOS in postnatal swine mesenteric artery

Reber

Clark

et al. 2002

American Journal of Physiology-Gastrointestinal and Liver Physi

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Developmental changes in the expression of endothelial nitric oxide synthase (eNOS) within the mesenteric artery of swine were studied in fetal (110 days postconception/117 days total gestation) and on postnatal days 1, 3, 10, and 30. Subjects in the 1-day-old group were subdivided into fed and nonfed. Transcription of eNOS was determined by real-time PCR, protein expression was evaluated by Western blotting, and hemodynamic and oxygenation parameters were measured within in situ gut loops before and after the administration of N G-monomethyl-l-arginine (l-NMMA). The abundance of eNOS mRNA remained steady throughout all ages. In contrast, expression of eNOS protein was twofold greater in the 1-day-old fed subjects compared with fetal or 1-day-old nonfed subjects. eNOS protein expression remained elevated on day 3, increased on day 10, and then declined to a level similar to the day 1 nonfed group by postnatal day 30. Intestinal vascular resistance was 31% lower in the day 1 fed group when compared to the day 1 nonfed group; resistance continued to decline through day 10 but then significantly increased on day 30. We conclude that the expression of eNOS changes within the mesenteric artery during early postnatal development at a posttranscriptional level.

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“…Arterial oxygen contents, organ blood flows, organ oxygen deliveries, as well as hepatic oxygen consumption (~~0~) and hepatic oxygen extraction (VL02/DL02) and cardiac output were plotted against hematocrit. We defined the mathematical relationships between independent and dependent variables using the least squares method based on covariance analysis (16). The advantage of this statistical method is that it takes into account the individual responses of the animals.…”

Section: Methodsmentioning

confidence: 99%

Blood Flow and Oxygen Delivery to the Organs of the Neonatal Lamb as a Function of Hematocrit

1986

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ABSTRACT. We chronically catheterized 15 newborn lambs (9.5 f 2.8 days) and measured the distribution of cardiac output by the radionuclide-microsphere technique at hematocrits ranging from 10 volumes % to 55 volumes %. Seven animals were made progressively anemic and eight polycythemic by means of exchange transfusions. Cardiac output and heart rate increased with decreasing hematocrit while whole body oxygen consumption showed a small decrease during severe anemia. Both cerebral and cardiac blood flow markedly increased during anemia which assured a relatively stable oxygen delivery to both organs. The changes seen for blood flow to the carcass (skin, bones, and muscle) were predictable from the effects of blood viscosity: small decreases in flow at the highest hematocrits and small increases in flow at the lowest hematocrits. Consequently, oxygen delivery was as low as 1 ml of oxygen/min/100 g at a hematocrit of 10 volumes %. Renal blood flow remained unchanged while oxygen delivery fell when hematocrit was decreased. Hepatic oxygenation was measured using a modification of the Fick principle. Hepatic blood flow showed only a small decrease as hematocrit increased and changed minimally during anemia resulting in a falling delivery of oxygen with anemia. A stable hepatic oxygen consumption was assured by a marked increase in oxygen extraction during anemia. Two differing organ responses to changes in hematocrit can be seen in the newborn: the brain and heart vary blood flow to assure an adequate delivery of oxygen while a number of other organs show less blood flow regulation and, most likely, vary oxygen removal from blood. Over a wide range of hematocrits, compensatory responses occur in the newborn which effectively prevent the development of tissue hypoxia. (Pediatr Res 20: 1274-1279, 1986 The physiologic responses that occur with isovolemic anemia and polycythemia reflect the continual interplay between the requirements for tissue oxygenation and the rheologic effects of changes in blood viscosity. While information is available concerning the changes in the distribution of cardiac output for both the fetus (1) and adults (2-8) with anemia and polycythemia, there are little data for the newborn. Two patterns of organ blood flow response can be seen in conditions of decreased oxygen availability: the brain, heart and adrenal glands meet their oxygen requirements by increasing organ blood flows; the majority of other organs regulate the extraction of oxygen by varying capil- lary density and the oxygen diffusion gradient. When both oxygen content and blood viscosity are changing, complex physiologic adjustments are clinically important for the maintenance of a stable oxygen delivery to the organs of the newborn. Both anemia and polycythemia can occur from a variety of causes related to chronic and acute events during pregnancy and delivery. Understanding the limits within which adequate tissue oxygenation occurs offers both prognostic and therapeutic possibilities in the care of infants, especially as we tr...

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Effects of varying hematocrit on intestinal oxygen uptake in neonatal lambs

Cited by 8 publications

References 0 publications

Effects of Abomasal Vegetable Oil Infusion on Splanchnic Nutrient Metabolism in Lactating Dairy Cows

Effects of Abomasal Vegetable Oil Infusion on Splanchnic Nutrient Metabolism in Lactating Dairy Cows

Developmental expression of eNOS in postnatal swine mesenteric artery

Blood Flow and Oxygen Delivery to the Organs of the Neonatal Lamb as a Function of Hematocrit

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