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Regulation of renal sympathetic nerve activity at birth. Am J Physiol 1996 Jan;270(1 Pt 2):R86-93

Date

01/01/1996

Pubmed ID

8769788

DOI

10.1152/ajpregu.1996.270.1.R86

Scopus ID

2-s2.0-0030029867   16 Citations

Abstract

The present studies were designed to assess the contribution of onset of respiration, separation from the placenta, and a decrease in environmental temperature on the increase in renal sympathetic nerve activity (RSNA) that occurs at birth. In the first series of experiments, heart rate (HR), mean arterial blood pressure (MABP), and RSNA were recorded in chronically instrumented near-term fetal sheep (n = 12) before and during in utero ventilation (V), V + oxygenation (V + O), and V + O + umbilical cord occlusion (V + O + CO). RSNA increased by 49 +/- 16% during V alone (P < 0.05), whereas no additional changes were seen with V + O or V + O + CO. HR and MABP did not change with any intervention. In a second series of experiments (n = 10), changes in fetal HR, MABP, and RSNA in response to in utero cooling were recorded. Cooling of the fetal core temperature by -3.1 +/- 0.2 degree C produced a rapid and sustained increase in RSNA (330 +/- 155%), HR (25 +/- 11%), and MABP (10 +/- 2%) consistent with generalized sympathoexcitation. In a third series of studies (n = 3), we found that brain stem transection between the rostral pons and posterior hypothalamus abolishes the increases in RSNA seen at birth. These results suggest that cooling is a major contributor to the postnatal rise in RSNA and that brain centers at the level of or above the hypothalamus are involved in mediating sympathoexcitation at birth.

Author List

Mazursky JE, Segar JL, Nuyt AM, 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

Animals
Animals, Newborn
Arteries
Brain Stem
Cold Temperature
Constriction
Delivery, Obstetric
Denervation
Female
Fetal Blood
Fetus
Hemodynamics
Kidney
Oxygen
Pregnancy
Respiration
Sheep
Sympathetic Nervous System
Umbilical Cord
jenkins-FCD Prod-478 d1509cf07a111124a2d122fd3df854cc0b993c00