Low birth weight and increased sympathetic activity.

Abstract

To the Editor: In a recent study on twins, IJzerman et al1 report an association between low birth weight and a short pre-ejection period at rest and during stress tests. They interpret their findings as evidence for an increased sympathetic nervous activity in low birth weight subjects. These data elucidate an important aspect in the regulation of the sympathetic system in low birth weight subjects. However, on the background of a study of our group, which examined muscle sympathetic nerve activity (MSNA) in low birth weight singletons,2 the interpretation of the results may have to be modified. In our study, sympathetic neural activity to the muscle vascular bed was determined by specific intraneural measurement. Under resting conditions, MSNA was lower in low birth weight subjects as compared with a control group with normal birth weight. Baroreflex function was also examined and showed normal functional properties. Additionally, sympathoexcitatory maneuvers (inspiratory apnea …