Effects of the pregnancy hormone relaxin on myocardial function.

摘要

The pregnancy hormone relaxin (RLX) has been recently discovered to mediate positive chronotropy and inotropy in the heart. However, these changes to myocardial function caused by RLX remain poorly understood, particularly at the myofilament level. Myofilament proteins are central to the process of myofibril contraction and, to date, no studies have examined the effect of RLX on myofilament function. This study provides evidence that RLX treatment of marine myocardium causes an increase in Ca2+ sensitivity of the myofilaments but no observable change in actomyosin Mg2+ ATPase activity at physiological levels of Ca2+. These results suggest the potential for RLX to increase efficiency of myofilament contraction. PKC inhibition abolished the RLX-mediated functional effects and PKC-delta levels were increased at the myofilament level in response to RLX treatment, indicating a key role for PKC to mediate RLX effects on the myofilaments.