Hyaluronate degradation affects ventricular function of the early postlooped embryonic rat heart in

Abstract Hyaluronic acid is the major glycosaminoglycan of the early cardiac extracellular matrix or "cardiac jelly, " yet little is known about its role in the ontogeny of early ventric-ular performance. To investigate the in situ effect of hyaluro-nate degradation on ventricular function, whole rat embryos were cultured in rat serum alone (control embryos) or rat serum plus 20 TRU/mL of Streptomyces hyaluronidase (treat-ment embryos) from gestational day 9.5 (before formation of the heart tube) through initial looping of the heart. Cardiac function was measured before looping (24 hours in culture) and immediately after looping (36 hours in culture) by video motion analysis of the external wall motion of the bulbus cordis and primitive ventricle. Degradation of hyaluronic acid in the treated embryos was confirmed by Alcian blue staining at pH 2.5. Significant increases in heart rate, circumferentia