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Impairment of cardiopulmonary baroreflexes during the newborn period. Am J Physiol 1995 Mar;268(3 Pt 2):H1343-51

Date

03/01/1995

Pubmed ID

7900887

DOI

10.1152/ajpheart.1995.268.3.H1343

Scopus ID

2-s2.0-0028923362   11 Citations

Abstract

The present study was designed to characterize the maturation of cardiopulmonary reflex control of renal sympathetic nerve activity (RSNA) independent of influences from the arterial baroreflex. Studies were conducted in conscious newborn lambs (3- to 7-days-old) (n = 16) and older lambs (6- to 8-wk-old) (n = 18). All animals underwent either sinoaortic denervation (SAD) or a sham procedure. Hemodynamic, humoral, neural, and renal responses to volume expansion (6% Dextran 70, 0.7 ml.kg-1.min-1 x 60 min) were recorded. Volume expansion resulted in a significant decrease (P < 0.05) in RSNA in intact newborn (-28.1 +/- 5.3% change from control) and older lambs (-19.4 +/- 10.1%). SAD totally abolished the sympathetic inhibition seen with volume expansion in newborn lambs (-3.6 +/- 5.7%) but not in older lambs (-25.6 +/- 8.4%). Right atrial pressure increased in a similar fashion in both newborn (intact: 5.6 +/- 0.5 mmHg; SAD: 6.1 +/- 0.8 mmHg) and older lambs (intact: 5.2 +/- 0.9 mmHg; SAD: 5.3 +/- 0.9 mmHg) and was not altered by SAD. The reflex bradycardia seen with volume expansion in newborn lambs was blocked by SAD. The present study demonstrates that, during the newborn period, the RSNA and heart rate responses to volume expansion are dependent mainly on the integrity of the arterial baroreflex. Furthermore, these studies suggest that cardiopulmonary reflex control of RSNA in response to volume expansion is impaired early in life and increases with maturation.

Author List

Merrill DC, McWeeny OJ, Segar JL, 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
Arginine Vasopressin
Atrial Natriuretic Factor
Baroreflex
Blood Pressure
Blood Volume
Cardiovascular Physiological Phenomena
Denervation
Hematocrit
Kidney
Oxygen
Renin
Respiratory Physiological Phenomena
Sheep
Sinoatrial Node
Sodium
Sympathetic Nervous System
jenkins-FCD Prod-486 e3098984f26de787f5ecab75090d0a28e7f4f7c0