TY - JOUR
T1 - Myosin-based contraction is not necessary for cardiac c-looping in the chick embryo
AU - Rémond, Mathieu C.
AU - Fee, Judy A.
AU - Elson, Elliot L.
AU - Taber, Larry A.
PY - 2006/10
Y1 - 2006/10
N2 - During the initial phase of cardiac looping, known as c-looping, the heart bends and twists into a c-shaped tube with the convex outer curvature normally directed toward the right side of the embryo. Despite intensive study for more than 80 years, the biophysical mechanisms that drive and regulate looping remain poorly understood, although some investigators have speculated that differential cytoskeletal contraction supplies the driving force for c-looping. The purpose of this investigation was to test this hypothesis. To inhibit contraction, embryonic chick hearts at stages 10-12 (10-16 somites, 33-48 h) were exposed to the myosin inhibitors 2,3-butanedione monoxime (BDM), ML-7, Y-27632, and blebbistatin. Experiments were conducted in both whole embryo culture and, to focus on bending alone, isolated heart culture. Measurements of heart stiffness and phosphorylation of the myosin regulatory light chains showed that BDM, Y-27632, and blebbistatin significantly reduced myocardial contractility, while ML-7 had a lesser effect. None of these drugs significantly affected looping during the studied stages. These results suggest that active contraction is not required for normal c-looping of the embryonic chick heart between stages 10 and 12.
AB - During the initial phase of cardiac looping, known as c-looping, the heart bends and twists into a c-shaped tube with the convex outer curvature normally directed toward the right side of the embryo. Despite intensive study for more than 80 years, the biophysical mechanisms that drive and regulate looping remain poorly understood, although some investigators have speculated that differential cytoskeletal contraction supplies the driving force for c-looping. The purpose of this investigation was to test this hypothesis. To inhibit contraction, embryonic chick hearts at stages 10-12 (10-16 somites, 33-48 h) were exposed to the myosin inhibitors 2,3-butanedione monoxime (BDM), ML-7, Y-27632, and blebbistatin. Experiments were conducted in both whole embryo culture and, to focus on bending alone, isolated heart culture. Measurements of heart stiffness and phosphorylation of the myosin regulatory light chains showed that BDM, Y-27632, and blebbistatin significantly reduced myocardial contractility, while ML-7 had a lesser effect. None of these drugs significantly affected looping during the studied stages. These results suggest that active contraction is not required for normal c-looping of the embryonic chick heart between stages 10 and 12.
KW - BDM
KW - Blebbistatin
KW - Cytoskeletal contraction
KW - Heart development
KW - Y-27632
UR - http://www.scopus.com/inward/record.url?scp=33745160125&partnerID=8YFLogxK
U2 - 10.1007/s00429-006-0094-0
DO - 10.1007/s00429-006-0094-0
M3 - Article
C2 - 16636777
AN - SCOPUS:33745160125
VL - 211
SP - 443
EP - 454
JO - Anatomy and Embryology
JF - Anatomy and Embryology
SN - 0340-2061
IS - 5
ER -