What question did this study set out to answer?

To assess whether the arterial baroreflex regulates heart rate and renal sympathetic nerve activity in response to blood pressure fluctuations in preterm fetal sheep.

December 25, 2008AJP Regulatory Integrative and Comparative Physiology

Is baroreflex control of sympathetic activity and heart rate active in the preterm fetal sheep?

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Why the study?

Does altered blood pressure affect fetal heart rate and renal sympathetic nerve activity in preterm fetal sheep?

Key Points

To assess whether the arterial baroreflex regulates heart rate and renal sympathetic nerve activity in response to blood pressure fluctuations in preterm fetal sheep.
Assessed preterm fetal sheep in utero at 102 ± 1 days of gestation (term = 140 days).
Pharmacologically induced blood pressure changes using phenylephrine for hypertension and sodium nitroprusside for hypotension while recording fetal heart rate and renal sympathetic nerve activity (RSNA).
Phenylephrine increased blood pressure from 38 ± 2 to 58 ± 3 mmHg and decreased heart rate from 177 ± 4 to 116 ± 8 bpm.
Sodium nitroprusside decreased blood pressure from 38 ± 2 to 26 ± 1 mmHg and increased heart rate from 182 ± 4 to 274 ± 8 bpm, with a significantly longer delay to 50% response during hypotension compared to hypertension (31 ± 8 s vs. 14 ± 5 s, P < 0.05).
No significant alterations in renal sympathetic nerve activity occurred in response to either drug challenge.

Structured PICO

Does altered blood pressure affect fetal heart rate and renal sympathetic nerve activity in preterm fetal sheep?

Population

Preterm fetal sheep in utero (102 +/- 1 days of gestation; term 140 days)

Intervention

Phenylephrine (to induce hypertension) and Sodium nitroprusside (to induce hypotension)

Outcome

Fetal heart rate and renal sympathetic nerve activity (RSNA) in response to altered blood pressuresurrogate

In preterm fetal sheep, baroreflex control of heart rate is active but renal sympathetic nerve activity does not respond to blood pressure changes, suggesting different maturational tempos for central autonomic responses.

Discussion

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Implication

Preserved baroreflex HR responses but absent RSNA reactivity in preterm fetal sheep; hypothesis-generating for differential autonomic maturation before clinical translation.

Cite This Study

Booth et al. (2008) studied this question.

synapsesocial.com/papers/6a7e10ad7981bc5195df3b05 https://doi.org/10.1152/ajpregu.90624.2008

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Implication

Preserved baroreflex HR responses but absent RSNA reactivity in preterm fetal sheep; hypothesis-generating for differential autonomic maturation before clinical translation.

Is baroreflex control of sympathetic activity and heart rate active in the preterm fetal sheep?

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Is baroreflex control of sympathetic activity and heart rate active in the preterm fetal sheep?

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider