Free and sulfoconjugated catecholamine responses at birth in newborn sheep

There have been little data on catecholamine sulfoconjugation in developing animals or humans. We studied the differences in free and sulfoconjugated catecholamines at birth in newborn sheep. Baseline concentrations of sulfoconjugated norepinephrine and epinephrine were the predominant form of circulating catecholamine, representing 77 +/- 4 and 65 +/- 12% of total circulating catecholamines, respectively. At birth the free epinephrine concentration increased 10-fold (49 +/- 27 to 653 +/- 21 pg/ml, respectively), and plasma free norepinephrine concentration rose 4-fold (307 +/- 92 to 1,178 +/- 389 pg/ml). In contrast, there was only a transient twofold increase in the sulfoconjugated epinephrine. There was no increase in the sulfoconjugated form of norepinephrine. These data demonstrate that, while the near-term newborn sheep has a well-developed mechanism for sulfoconjugation of circulating catecholamines, this does not occur rapidly. During the logarithmic increases of circulating catecholamines at birth, there are not commensurate increases in the concentration of sulfoconjugated norepinephrine or epinephrine. Thus sulfoconjugation does not appear to represent a significant mechanism for inactivation of the high circulating levels of catecholamines seen at birth.

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Effect of physical training on the capacity to secrete epinephrine

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.1.11 ◽

1988 ◽

Vol 64 (1) ◽

pp. 11-16 ◽

Cited By ~ 31

Author(s):

M. Kjaer ◽

H. Galbo

Keyword(s):

Hypobaric Hypoxia ◽

Plasma Norepinephrine ◽

Plasma Epinephrine ◽

O2 Uptake ◽

Acute Hypobaric Hypoxia ◽

Arterial Pco2 ◽

Norepinephrine Concentration ◽

Arterial Po2 ◽

Secretory Capacity ◽

Epinephrine Concentration

Epinephrine responses to hypoglycemia and to identical relative work loads have been shown to be higher in endurance-trained athletes than in untrained subjects. To test the hypothesis that training increases the adrenal medullary secretory capacity, we studied the effects of glucagon (1 mg/70 kg iv), acute hypercapnia (inspired O2 fraction = 7%), and acute hypobaric hypoxia (inspired Po2 = 87 Torr), respectively, on the epinephrine concentration in arterialized hand vein blood in eight endurance-trained athletes [T, O2 uptake = 66 (62-70) ml.min-1.kg-1] and seven sedentary males [C, O2 uptake = 46 (41-50)]. In response to identical increments in glucagon concentrations, plasma epinephrine increased more in T than in C subjects [0.87 +/- 0.11 vs. 0.38 +/- 0.14 (SE) nmol/l, P less than 0.05]. In response to hypercapnia [arterial PCO2 = 56 +/- 0.7 Torr (T) and 55 +/- 0.4 (C), P greater than 0.05], the increment in epinephrine was significant in T (0.38 +/- 0.11 nmol/l) but not (P less than 0.1) in C subjects (0.22 +/- 0.11). Hypoxia [arterial PO2 = 42 +/- 2 Torr (T) and 41 +/- 2 (C), P greater than 0.05] increased epinephrine in T (0.22 +/- 0.10 nmol/l, P less than 0.05) but not in C subjects (0.01 +/- 0.07). The plasma norepinephrine concentration never changed, whereas heart rate always increased, the increase being higher (P less than 0.05) in T than in C subjects only during hypercapnia. The results indicate that training increases the capacity to secrete epinephrine.

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Relation of thyroid state to myocardial catecholamine concentration

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1963.205.6.1270 ◽

1963 ◽

Vol 205 (6) ◽

pp. 1270-1274 ◽

Cited By ~ 9

Author(s):

George S. Kurland ◽

Rupert P. Hammond ◽

A. Stone Freedberg

Keyword(s):

Body Weight ◽

Basal Metabolic Rate ◽

Fluorescence Spectra ◽

Alumina Column ◽

Thyroid State ◽

Norepinephrine Concentration ◽

Norepinephrine Content ◽

Alumina Column Chromatography ◽

Catecholamine Concentration ◽

Epinephrine Concentration

The myocardial catecholamine content was measured in euthyroid, thyrotoxic, and hypothyroid rabbits. Male rabbits were made thyrotoxic by injection of l-thyroxine, or were rendered hypothyroid by injection of I131. Body weight, basal metabolic rate, serum protein-bound iodine, and appearance were used as criteria of thyroid state. Myocardial norepinephrine and epinephrine concentrations were measured, after alumina column chromatography, by a modification of the trihydroxyindole method. Fluorescence spectra and paper chromatographic analyses confirmed the identity of the trihydroxyindole-fluorescing material, and revealed no extraneous fluorescing substances. In the heart of the euthyroid rabbit, epinephrine concentration averaged 0.3 ± .2 (sd) µg/g in the atrium, and 0.06 ± .03 µg/g in the ventricle. Norepinephrine concentration averaged 2.9 ± .4 µg/g in the atrium, and 2.2 ± .3 µg/g in the ventricle. In thyrotoxicosis, atrial epinephrine and norepinephrine concentrations were decreased, ventricular epinephrine was unchanged, and ventricular norepinephrine was decreased. In hypothyroidism, atrial epinephrine and norepinephrine were decreased and ventricular epinephrine was unchanged, but in the hypothyroid ventricle, norepinephrine content was markedly increased.

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Follow-up into young adulthood after cardiopulmonary resuscitation in term and near-term newborn infants. II. Neuropsychological consequences

Acta Paediatrica ◽

10.1111/j.1651-2227.2002.tb00132.x ◽

2007 ◽

Vol 91 (11) ◽

pp. 1218-1226 ◽

Cited By ~ 7

Author(s):

G Viggedal ◽

E Lundälv ◽

G Carlsson ◽

I Kjellmer

Keyword(s):

Cardiopulmonary Resuscitation ◽

Young Adulthood ◽

Newborn Infants ◽

Term Newborn ◽

Near Term

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Plasma prostaglandins, renin, and catecholamines at rest and during exercise in hypertensive humans

Journal of Applied Physiology ◽

10.1152/jappl.1982.53.4.891 ◽

1982 ◽

Vol 53 (4) ◽

pp. 891-894 ◽

Cited By ~ 3

Author(s):

P. Lijnen ◽

R. Fagard ◽

J. Staessen ◽

A. Amery

Keyword(s):

Exercise Test ◽

Pulmonary Arteries ◽

Plasma Renin ◽

Work Load ◽

Bicycle Ergometer ◽

Graded Exercise ◽

Circulating Levels ◽

Catecholamine Concentration ◽

Epinephrine Concentration ◽

Final Work

Plasma prostaglandins (PGE and PGF alpha), catecholamine concentration, and plasma renin activity (PRA) were measured during an uninterrupted graded exercise test on the bicycle ergometer in 11 hypertensive patients. Blood was withdrawn from the brachial and pulmonary arteries after 30 min of recumbent rest, after 15 min of rest sitting, and at the final work load of the exercise test, which averaged 143 +/- 16.5 W. Exercise did not provoke a significant change in these plasma PGE or PGF alpha concentrations, whereas a rise (P less than 0.001) in arterial PRA and (nor)epinephrine concentration was observed. It is thus unlikely that PGE or PGF alpha is an important determinant of PRA release during exercise, although circulating levels of PGE and PGF alpha do not necessarily reflect release rate or activity in the kidney.

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Vitamin D status and metabolism in an ovine pregnancy model: effect of long-term, high-altitude hypoxia

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00494.2015 ◽

2016 ◽

Vol 310 (11) ◽

pp. E1062-E1071 ◽

Cited By ~ 2

Author(s):

Ravi Goyal ◽

Tara L. Billings ◽

Trina Mansour ◽

Courtney Martin ◽

David J. Baylink ◽

...

Keyword(s):

Vitamin D ◽

High Altitude ◽

Plasma Levels ◽

Vitamin D Status ◽

Molecular Determinants ◽

Near Term ◽

Specific Regulation ◽

Circulating Levels

Vitamin D status increases during healthy mammalian pregnancy, but the molecular determinants remain uncharacterized. The first objective of this study was to determine the effects of pregnancy, and the second objective was to examine the role of chronic hypoxia on vitamin D status and metabolism in an ovine model. We analyzed the plasma levels of cholecalciferol, 25-OH-D, and 1α,25-(OH)2D in nonpregnant ewes, near-term pregnant ewes, and their fetuses exposed to normoxia (low altitude) or hypoxia (high-altitude) for 100 days. Hypoxic sheep had increased circulating levels of 25-OH-D and 1α,25-(OH)2D compared with normoxic sheep. Hypoxia increases in 25-OH-D were associated with increased expression of renal 25-hydroxylases CYP2R1 and CYP2J. Pregnancy did not increase further the plasma levels of 25-OH-D, but it significantly increased those of the active metabolite, 1α,25-(OH)2D, in both normoxic and hypoxic ewes. Increased bioactivation of vitamin D correlated with increased expression of the vitamin D-activating enzyme CYP27b1 and decreased expression of the inactivating enzyme CYP24a1 in maternal kidneys and placentas. Hypoxia increased parathyroid hormone levels and further increased renal CYP27b1. Pregnancy and hypoxia decreased the expression of vitamin D receptor (VDR) in maternal kidney and lung, with opposite effects on placental VDR. We conclude that ovine pregnancy is a model of increased vitamin D status, and long-term hypoxia further improves vitamin D status due to pregnancy- and hypoxia-specific regulation of VDR and metabolic enzymes.

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Prevention of bilirubin encephalopathy in term and near-term newborn infants

Clinical Risk ◽

10.1258/135626206777657703 ◽

2006 ◽

Vol 12 (4) ◽

pp. 131-135

Author(s):

Donal Manning

Keyword(s):

Newborn Infants ◽

Term Newborn ◽

Bilirubin Encephalopathy ◽

Near Term

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Propofol Fails to Attenuate the Cardiovascular Response to Rapid Increases in Desflurane Concentration

Anesthesiology ◽

10.1097/00000542-199601000-00009 ◽

1996 ◽

Vol 84 (1) ◽

pp. 75-80 ◽

Cited By ~ 9

Author(s):

Malcolm Daniel ◽

Edmond I Eger ◽

Richard B. Weiskopf ◽

Mariam Noorani

Keyword(s):

Heart Rate ◽

Cardiovascular Response ◽

Peak Plasma ◽

Random Order ◽

Arterial Blood ◽

Norepinephrine Concentration ◽

Desflurane Concentration ◽

End Tidal ◽

Catecholamine Concentration ◽

Epinephrine Concentration

Background A rapid increase in desflurane concentration to greater than 1 MAC transiently increases heart rate, arterial blood pressure, and circulating catecholamine concentration. Because propofol decreases sympathetic outflow, it was hypothesized that propofol would blunt these responses. Methods To test this hypothesis, five healthy male volunteers were studied three times. After induction of anesthesia with 2 mg.kg-1 propofol, anesthesia was maintained with 4% end-tidal desflurane in oxygen (0.55 MAC) via an endotracheal tube for 32 min. On separate occasions, in random order, either no propofol or 2 mg.kg-1 propofol was administered either 2 or 5 min before increasing end-tidal desflurane concentration from 4% to 8%. Results Without propofol pretreatment, the increase to 8% desflurane transiently increased heart rate (from 63 +/- 3 beats/min to 108 +/- 5 beats/min, mean +/- SEM; P < 0.01), mean arterial pressure (from 73 +/- 1 mmHg to 118 +/- 6 mmHg; P < 0.01), and epinephrine concentration (from 14 +/- 1 pg.ml-1 to 279 +/- 51 pg.ml-1; P < 0.05). There was no significant change in norepinephrine concentration (from 198 +/- 37 pg.ml-1 to 277 +/- 46 pg.ml-1). The peak plasma epinephrine concentration was attenuated by each propofol pretreatment (158 +/- 35 pg.ml-1, propofol given 2 min before, and 146 + 41 pg.ml-1, propofol given 5 min before; P < 0.05), but neither propofol pretreatment modified the cardiovascular or norepinephrine responses. Conclusions Although able to blunt the increase in epinephrine concentration, propofol 2 mg.kg-1 propofol does no attenuate the transient cardiovascular response to a rapid increase in desflurane concentration to greater than 1 MAC.

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Increased end-expiratory pressures improve lung function in near-term newborn rabbits with elevated airway liquid volume at birth

Journal of Applied Physiology ◽

10.1152/japplphysiol.00918.2020 ◽

2021 ◽

Author(s):

Erin Victoria McGillick ◽

Arjan B. te Pas ◽

Michelle Kathleen Croughan ◽

Kelly J. Crossley ◽

Megan J. Wallace ◽

...

Keyword(s):

Lung Function ◽

Caesarean Section ◽

Respiratory Distress ◽

Lung Compliance ◽

Respiratory Support ◽

Respiratory Morbidity ◽

Liquid Volume ◽

Term Newborn ◽

Lung Aeration ◽

Near Term

Approximately 53% of near-term newborns admitted into intensive care, experience respiratory distress. These newborns are commonly delivered by caesarean section and have elevated airway liquid volumes at birth, which can cause respiratory morbidity. We investigated the effect of providing respiratory support with a positive end expiratory pressure (PEEP) of 8cmH2O on lung function in newborn rabbit kittens with elevated airway liquid volumes at birth.Near-term rabbits (30d; term=32d) with airway liquid volumes that corresponded to vaginal delivery (~7mL/kg, Control, n=11) or caesarean section (~37mL/kg; Elevated Liquid (EL), n=11) were mechanically ventilated (tidal volume=8mL/kg). The PEEP was changed after lung aeration from 0 to 8 to 0 cmH2O (Control, n=6; EL, n=6) and in a separate group of kittens, PEEP was changed after lung aeration from 8 to 0 to 8 cmH2O (Control, n=5; EL, n=5). Lung function (ventilator parameters, compliance, lung gas volumes and distribution of gas within the lung) was evaluated using plethysmography and synchrotron-based phase contrast X-ray imaging. EL kittens initially receiving 0 cmH2O PEEP had reduced functional residual capacities and lung compliance, requiring higher inflation pressures to aerate the lung compared to Control kittens. Commencing ventilation with 8 cmH2O PEEP mitigated the adverse effects of EL, increasing lung compliance, functional residual capacity and the uniformity and distribution of lung aeration, but did not normalize aeration of the distal airways. Respiratory support with PEEP supports lung function in near-term newborn rabbits with elevated airway liquid volumes at birth who are at greater risk of suffering respiratory distress.

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