Cardiovascular responses to graded degrees of hypoxaemia in the llama fetus

Llanos, AJ; Riquelme, RA; Moraga, F A; Cabello, Gertrudis; Parer, J. T.

doi:10.1071/rd9950549

Cited by 27 publications

(12 citation statements)

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“…Maternal and fetal surgeries were carried out on consecutive days using well‐established techniques, which have previously been described in detail (Benavides et al 1989; Llanos et al 1995). Following food and water deprivation for 24 h, the maternal llamas were premedicated with atropine (0.04 mg kg −1 , i.m.…”

Section: Methodsmentioning

confidence: 99%

Fetal brain hypometabolism during prolonged hypoxaemia in the llama

Ebensperger

Herrera

et al. 2005

The Journal of Physiology

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In this study we looked for additional evidence to support the hypothesis that fetal llama reacts to hypoxaemia with adaptive brain hypometabolism. We determined fetal llama brain temperature, Na + and K + channel density and Na + -K + -ATPase activity. Additionally, we looked to see whether there were signs of cell death in the brain cortex of llama fetuses submitted to prolonged hypoxaemia. Ten fetal llamas were instrumented under general anaesthesia to measure pH, arterial blood gases, mean arterial pressure, heart rate, and brain and core temperatures. Measurements were made 1 h before and every hour during 24 h of hypoxaemia (n = 5), which was imposed by reducing maternal inspired oxygen fraction to reach a fetal arterial partial pressure of oxygen (P a,O 2 ) of about 12 mmHg. A normoxaemic group was the control (n = 5). After 24 h of hypoxaemia, we determined brain cortex Na + -K + -ATPase activity, ouabain binding, and the expression of NaV1.1, NaV1.2, NaV1.3, NaV1.6, TREK1, TRAAK and K ATP channels. The lack of brain cortex damage was assessed as poly ADP-ribose polymerase (PARP) proteolysis. We found a mean decrease of 0.56• C in brain cortex temperature during prolonged hypoxaemia, which was accompanied by a 51% decrease in brain cortex Na + -K + -ATPase activity, and by a 44% decrease in protein content of NaV1.1, a voltage-gated Na + channel. These changes occurred in absence of changes in PARP protein degradation, suggesting that the cell death of the brain was not enhanced in the fetal llama during hypoxaemia. Taken together, these results provide further evidence to support the hypothesis that the fetal llama responds to prolonged hypoxaemia with adaptive brain hypometabolism, partly mediated by decreases in Na + -K + -ATPase activity and expression of NaV channels.

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Section: Methodsmentioning

confidence: 99%

Fetal brain hypometabolism during prolonged hypoxaemia in the llama

Ebensperger

Herrera

et al. 2005

The Journal of Physiology

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“…For example, NWC exhibit increased oxygen conductance of red blood cells compared to foals and calves, characterized by both an increased hemoglobin‐oxygen affinity and an increased oxygen extraction from tissues. Because of this, NWC are able to maintain cardiac output and brain‐blood flow in the face of hypoxemia . .…”

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confidence: 99%

Clinical Findings and Survival in 56 Sick Neonatal New World Camelids

Bertin

Squires

Kritchevsky

et al. 2014

Veterinary Internal Medicne

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BackgroundInformation pertaining to clinical presentation and outcome of neonatal New World camelids (NWC) is limited when compared to calves and foals.HypothesisValues of variables at admission and subsequent treatment would predict survival in sick neonatal NWC.AnimalsFifty‐six client‐owned sick neonatal NWC presented over a 10‐year period to the Purdue University Veterinary Teaching Hospital.MethodsA retrospective study was performed. Inclusion criteria were NWC less than 30 days of age with complete medical records that presented between 2000 and 2010.ResultsThe median age at presentation was 1 day (range 1–20). The most common diagnoses were systemic inflammatory response syndrome (50%), congenital defects (41%), ophthalmic lesions (21%), sepsis (16%), and gastrointestinal diseases (16%). Sixty‐six percent of NWC survived to discharge. Clinicopathologic findings on admission were variable and not specific for disorders. Factors associated with survival were absence of choanal atresia (P = .001, OR: 55.9 [2.5–1,232]), administration of llama plasma (P = .013, OR: 4.9 [1.4–17.7]), and antimicrobial treatment with trimethoprim‐sulfamethoxazole (TMS) (P = .016, OR: 6.5 [1.3–32.2]).Conclusions and Clinical ImportanceThe use of antibiotics, particularly TMS, and llama plasma are recommended in sick neonatal NWC. Results from this study could contribute toward defining a NWC‐specific sepsis scoring system.

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“…Maternal and fetal surgeries were carried out on consecutive days using well-established techniques previously described in detail (4,27). Briefly, following food and water deprivation for 24 h, the pregnant llamas were premedicated with atropine (1 mg im, Atropina Sulfato, Laboratorio Chile, Santiago, Chile).…”

Section: Methodsmentioning

confidence: 99%

“…Characteristically, the fetal llama has a greater total peripheral vascular resistance than the sheep, both in normoxemia and in hypoxemia (28,34). Furthermore, unlike fetuses of lowland species (34), the fetal llama responds to acute hypoxemia with a marked peripheral vasoconstriction and with little or no increase in cerebral blood flow (13,14,27,29). This response to hypoxemia suggests differences in the gain of chemoreflexes or in the balance between endocrine and autocrine vasoconstrictor and vasodilator mechanisms between fetuses of highland and lowland species.…”

mentioning

confidence: 92%

Vasodilator tone in the llama fetus: the role of nitric oxide during normoxemia and hypoxemia

Sanhueza¹,

Riquelme²,

Herrera³

et al. 2005

American Journal of Physiology-Regulatory, Integrative and Comp

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The fetal llama responds to hypoxemia, with a marked peripheral vasoconstriction but, unlike the sheep, with little or no increase in cerebral blood flow. We tested the hypothesis that the role of nitric oxide (NO) may be increased during hypoxemia in this species, to counterbalance a strong vasoconstrictor effect. Ten fetal llamas were operated under general anesthesia. Mean arterial pressure (MAP), heart rate, cardiac output, total vascular resistance, blood flows, and vascular resistances in cerebral, carotid and femoral vascular beds were determined. Two groups were studied, one with nitric oxide synthase (NOS) blocker N(G)-nitro-L-arginine methyl ester (L-NAME), and the other with 0.9% NaCl (control group), during normoxemia, hypoxemia, and recovery. During normoxemia, L-NAME produced an increase in fetal MAP and a rapid bradycardia. Cerebral, carotid, and femoral vascular resistance increased and blood flow decreased to carotid and femoral beds, while cerebral blood flow did not change significantly. However, during hypoxemia cerebral and carotid vascular resistance fell by 44% from its value in normoxemia after L-NAME, although femoral vascular resistance progressively increased and remained high during recovery. We conclude that in the llama fetus: 1) NO has an important role in maintaining a vasodilator tone during both normoxemia and hypoxemia in cerebral and femoral vascular beds and 2) during hypoxemia, NOS blockade unmasked the action of other vasodilator agents that contribute, with nitric oxide, to preserving blood flow and oxygen delivery to the tissues.

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Cardiovascular responses to graded degrees of hypoxaemia in the llama fetus

Cited by 27 publications

References 0 publications

Fetal brain hypometabolism during prolonged hypoxaemia in the llama

Fetal brain hypometabolism during prolonged hypoxaemia in the llama

Clinical Findings and Survival in 56 Sick Neonatal New World Camelids

Vasodilator tone in the llama fetus: the role of nitric oxide during normoxemia and hypoxemia

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