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The Journal of physiology2006; 572(Pt 1); 155-164; doi: 10.1113/jphysiol.2006.105635

Development of baroreflex function and hind limb vascular reactivity in the horse fetus.

Abstract: This study investigated, in vivo, the mechanisms underlying the development of cardiovascular function in the horse fetus, with particular relevance to baroreflex function and hind limb vascular arterial reactivity to constrictor agonists. Under general anaesthesia, vascular catheters were inserted and a Transonic flow probe was implanted around one of the metatarsal arteries of 13 horse fetuses, either at 0.6 of gestation (n= 6) or at 0.9 of gestation (n= 7, term approximately 335 days). At least 5 days after surgery, pressor, vasoconstrictor and cardiac chronotropic responses to exogenous bolus doses of phenylephrine, angiotensin II and arginine vasopressin were recorded. Fetal cardiac baroreflex slopes were obtained using the peak pressor and heart rate responses to increasing doses of phenylephrine. Fetal treatment with phenylephrine, angiotensin II and vasopressin produced significant changes in arterial blood pressure, hind limb vascular resistance and heart rate. Pressor and vasopressor responses to all agonists were greater at 0.9 than at 0.6 of gestation; however, fetal cardiac baroreflex sensitivity decreased with advancing gestational age. Correlation analysis revealed that fetal plasma cortisol rather than gestational age was a greater determinant of pressor and vasopressor reactivity. In contrast, gestational age rather than cortisol better determined heart rate and baroreflex responsiveness in the equine fetus. The data show that development of cardiovascular function in the equine fetus occurs via cortisol-dependent and -independent pathways.
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Publication Date: 2006-02-09 PubMed ID: 16469779PubMed Central: PMC1779647DOI: 10.1113/jphysiol.2006.105635Google Scholar: Lookup
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  • Journal Article
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  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article focuses on understanding the development of cardiovascular function in horse fetuses, primarily the baroreflex function and reactivity of hind limb arteries to constrictor agents. The study found that both cortisol-dependent and independent pathways contribute to this development and factors like fetal plasma cortisol and gestational age strongly influence various aspects.

Methodology

  • The study was conducted in-vivo on 13 horse fetuses either at 60% of gestation (n=6) or at 90% of gestation (n=7).
  • Detailed investigation was achieved under general anesthesia by inserting vascular catheters and implanting a Transonic flow probe around one of the metatarsal arteries of the fetuses.
  • The researchers observed the effects of administering exogenous bolus doses of phenylephrine, angiotensin II, and arginine vasopressin at least five days after surgery.
  • They gauged fetal cardiac baroreflex slopes by using the peak pressor and heart rate responses to varying doses of phenylephrine.

Findings

  • The administered treatments invoked significant changes in the arterial blood pressure, hind limb vascular resistance, and heart rate of the fetuses.
  • The pressor and vasopressor responses to all the constrictor agents were greater at 90% gestation as compared to 60%; however, the baroreflex sensitivity of the fetal cardiac decreased with progression in gestational age.

Correlation Analysis

  • The researchers drew connections between the fetal plasma cortisol, gestational age, and effects on pressor, vasopressor, heart rate, and baroreflex sensitivity.
  • They found that fetal plasma cortisol was a more significant determinant of pressor and vasopressor reactivity than gestational age.
  • Conversely, gestational age was a better determinant of heart rate and baroreflex responsiveness in the horse fetus than cortisol.

Conclusion

  • This study showcased that the cardiovascular development in equine fetuses occurs through both cortisol-dependent and independent pathways.
  • The results improve understanding of hormonal and gestational effects on fetal cardiovascular development, crucial for effective veterinary care and prenatal equine health.

Cite This Article

APA
O'Connor SJ, Ousey JC, Gardner DS, Fowden AL, Giussani DA. (2006). Development of baroreflex function and hind limb vascular reactivity in the horse fetus. J Physiol, 572(Pt 1), 155-164. https://doi.org/10.1113/jphysiol.2006.105635

Publication

The Journal of physiology
ISSN: 0022-3751
NlmUniqueID: 0266262
Country: England
Language: English
Volume: 572
Issue: Pt 1
Pages: 155-164

Researcher Affiliations

O'Connor, Susie J
  • Department of Physiology, University of Cambridge, Cambridge CB2 3EG, UK. dag26@cam.ac.uk
Ousey, Jenny C
    Gardner, David S
      Fowden, Abigail L
        Giussani, Dino A

          MeSH Terms

          • Animals
          • Baroreflex / physiology
          • Fetal Blood / metabolism
          • Hindlimb / blood supply
          • Hindlimb / embryology
          • Horses / embryology
          • Horses / physiology
          • Hydrocortisone / blood
          • Vasomotor System / physiology

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          Citations

          This article has been cited 2 times.
          1. Allison BJ, Brain KL, Niu Y, Kane AD, Herrera EA, Thakor AS, Botting KJ, Cross CM, Itani N, Shaw CJ, Skeffington KL, Beck C, Giussani DA. Altered Cardiovascular Defense to Hypotensive Stress in the Chronically Hypoxic Fetus. Hypertension 2020 Oct;76(4):1195-1207.
            doi: 10.1161/HYPERTENSIONAHA.120.15384pubmed: 32862711google scholar: lookup
          2. Skeffington KL, Beck C, Itani N, Giussani DA. Isolating the direct effects of adverse developmental conditions on in vivo cardiovascular function at adulthood: the avian model. J Dev Orig Health Dis 2018 Aug;9(4):460-466.
            doi: 10.1017/S2040174418000247pubmed: 29692274google scholar: lookup
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