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Cardiopulmonary and arterial baroreflex responses to acute volume expansion during fetal and postnatal development. Am J Physiol 1994 Oct;267(4 Pt 2):H1467-75

Date

10/01/1994

Pubmed ID

7943393

DOI

10.1152/ajpheart.1994.267.4.H1467

Scopus ID

2-s2.0-0028063270   7 Citations

Abstract

Recent studies demonstrated that renal denervation had no effect on the natriuretic response to volume expansion (VE) in fetal sheep, suggesting that the sensitivity of the cardiopulmonary reflex in response to VE is impaired in the fetus. To test this hypothesis, we investigated the renal sympathetic nerve activity (RSNA) and heart rate (HR) responses to 20 and 50% intravascular VE in fetal (130-135 days gestation; term 145 days) (n = 7), newborn (n = 8), and 6- to 8-wk-old sheep (n = 9). Despite similar increases in right atrial pressure (RAP) in the three groups, 20% VE had no significant effect on RSNA and HR in fetal sheep but significantly decreased RSNA in newborn (-22.8 +/- 7.3%) and 6- to 8-wk-old sheep (-32.1 +/- 11.7%). Bradycardic responses to VE were also observed in both newborn (from 237 +/- 6 to 200 +/- 12 beats/min) and 6- to 8-wk-old sheep (from 170 +/- 9 to 140 +/- 9 beats/min). A 50% VE had no significant effect on fetal RSNA and HR, whereas it increased RAP by 6.8 +/- 0.9 mmHg. In addition, we tested the hypothesis that interactions between cardiopulmonary and arterial baroreflexes in response to VE change during development. We found that 20 and 50% VE shifted the RSNA and HR arterial baroreflex response curves to the right in the fetus but had no significant effects on the gain of the arterial baroreflex curves in either fetal, newborn, or 6- to 8-wk-old sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Merrill DC, Segar JL, McWeeny OJ, Smith BA, Robillard JE

Author

Jeffrey L. Segar MD Professor in the Pediatrics department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Aging
Animals
Animals, Newborn
Baroreflex
Blood Pressure
Blood Volume
Embryonic and Fetal Development
Female
Fetus
Gestational Age
Heart Rate
Kidney
Phenylephrine
Pregnancy
Pulmonary Circulation
Renal Circulation
Sheep
Sympathetic Nervous System
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