HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 98/3/1013    most recent 01083.2004v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Debrah, D. O. Articles by Shroff, S. G. Search for Related Content PubMed PubMed Citation Articles by Debrah, D. O. Articles by Shroff, S. G.

Effects of relaxin on systemic arterial hemodynamics and mechanical properties in conscious rats: sex dependency and dose response

¹Department of Bioengineering, University of Pittsburgh, and ²Departments of Obstetrics, Gynecology and Reproductive Sciences, and of Cell Biology and Physiology, University of Pittsburgh School of Medicine and Magee-Womens Research Institute, Pittsburgh, Pennsylvania; and ³Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico

Submitted 29 September 2004 ; accepted in final form 10 October 2004

We previously showed that chronic administration of recombinant human relaxin (rhRLX; 4 µg/h) to conscious female, nonpregnant rats to reach serum levels corresponding to early to midgestation (20 ng/ml) increases cardiac output (CO) and global arterial compliance (AC) and decreases systemic vascular resistance (SVR), comparable to changes observed in midterm pregnancy. The goals of this study were to test whether chronic administration of rhRLX (4 µg/h) to conscious male rats will yield similar changes in CO and systemic arterial load and to determine whether higher infusion rates of rhRLX (50 µg/h) administered to nonpregnant female rats yielding serum concentrations corresponding to late pregnancy (80 ng/ml) will further modify CO and SVR and global AC comparable to late gestation. CO and systemic arterial load, as quantified by SVR and AC, were obtained by using the same methods as in our previous studies. With respect to baseline, chronic rhRLX administration to male rats over 10 days at 4 µg/h increased both CO (20.5 ± 4.2%) and AC (19.4 ± 6.9%) and reduced SVR (12.7 ± 3.9%). These results were comparable to those elicited by the hormone in nonpregnant female rats. In contrast, neither acute (over 4 h) nor chronic (over 6 days) infusion of the higher dose of rhRLX administered to conscious female rats resulted in significant changes in CO, AC, or SVR from baseline. We conclude that 1) rhRLX increases CO and AC and reduces SVR irrespective of sex, and 2) the rhRLX dose response is biphasic insofar as significant alterations in CO and systemic arterial load fail to occur at high serum concentrations.

arteries; vasodilation; arterial compliance; arterial resistance