Journal article
Changes in ovine renal sympathetic nerve activity and baroreflex function at birth
American journal of physiology. Heart and circulatory physiology, Vol.267(5), pp.H1824-H1832
11/01/1994
DOI: 10.1152/ajpheart.1994.267.5.H1824
PMID: 7977812
Abstract
The purposes of this study were to characterize the changes in renal sympathetic nerve activity (RSNA) and baroreflex function at birth in conscious sheep. One hour after delivery by cesarean section, RSNA increased by 239 +/- 24% compared with fetuses. The upper and lower plateau values of the baroreflex function curves for RSNA, expressed as the percent maximum achieved in the fetus, were greater (P < 0.05) at 1 h (260 +/- 41 and 142 +/- 40%) and 5 h of age (254 +/- 34 and 100 +/- 19%) than in fetuses (100 and 10 +/- 3%), respectively. Curve midpoint pressures also were higher (P < 0.05) at 1 h (62 +/- 3 mmHg) and 5 h (66 +/- 4 mmHg) than in fetuses (51 +/- 2 mmHg). No changes in the sensitivity (gain) of the RSNA response to baroreceptor stimulation were seen. The baroreflex response curves for heart rate showed similar increases in the curve midpoint pressures, while gain did not change. To determine whether the high circulating levels of angiotensin II (ANG II) in the newborn period contribute to the rise in RSNA or the resetting of the baroreflex toward higher pressures, the angiotensin-converting-enzyme inhibitor, enalaprilat, was administered to five lambs before delivery. No differences in the increase in RSNA after birth were detected between control and treated animals. The curve midpoint pressures of both the RSNA and heart rate baroreflex response curves were significantly less (P < 0.05) in the treated compared with control lambs.
Details
- Title: Subtitle
- Changes in ovine renal sympathetic nerve activity and baroreflex function at birth
- Creators
- J. L. Segar - University of IowaJ. E. Mazursky - University of IowaJ. E. Robillard - University of Iowa
- Resource Type
- Journal article
- Publication Details
- American journal of physiology. Heart and circulatory physiology, Vol.267(5), pp.H1824-H1832
- DOI
- 10.1152/ajpheart.1994.267.5.H1824
- PMID
- 7977812
- ISSN
- 0363-6135
- eISSN
- 1522-1539
- Language
- English
- Date published
- 11/01/1994
- Academic Unit
- Molecular Physiology and Biophysics; Nephrology, Dialysis and Transplantation; Stead Family Department of Pediatrics; Medicine Administration
- Record Identifier
- 9984773402502771
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