Abnormal Myocardial and Coronary Vasculature Development in Experimental Hypoxia

Abstract

Freshly isolated quail embryonic heart at Hamburger‐Hamilton stage 28, stained with voltage sensitive dye and optically mapped to reveal ventricular activation pattern (indicated by color isochrones in 1 ms intervals). The activation wave sweeps from left to right in the direction of the arrow. Maturation of ventricular activation patterns is accelerated by hypoxic incubation, as described in detail together with other changes in ventricular angio‐ and myoarchitecture. From “Abnormal Myocardial and coronary Vasculature Development in Experimental Hypoxia,” by Ondrej Nanka, et al., on page 1187, in this issue.

IGF signaling directs ventricular cardiomyocyte proliferation during embryonic heart development

“…In one study (Pennisi et al, 2003) in which interference with epicardium formation in chick embryos led to a clearly evident ventricular wall phenotype, there was only an 11% reduction in proliferation rate as measured by BrdU incorporation; however, clonal analysis revealed the loss of one cycle of cell division, and those authors emphasized that one fewer round of cell division over a period of a few days would result in a 50% reduction in compact zone thickness. In experimental models with severe compact zone thinning, the extent to which compact zone proliferation is decreased does not exceed 50% (Kastner et al, 1997;Bushdid et al, 2003) and, in more typical cases, still with dramatic compact zone hypoplasia, reductions in the range of 30-45% were seen (Lavine et al, 2005;Zamora et al, 2007;Lavine et al, 2008;Nanka et al, 2008;Peng et al, 2008). IGF signaling deficiency has a phenotypic impact of this magnitude (Fig.…”

Effects of mechanical loading on early conduction system differentiation in the chick

“…Freshly isolated hearts from ED3, -4, and -5 chick embryos together with unloaded and loaded cultured hearts were stained with voltage-sensitive dye 4-{␤-[2(di-n-butylamino)-6-napthyl]vinyl}pyridinium (Invitrogen) and subjected to optical map- ping of epicardial action potential propagation as recently described in detail (12). The spatial resolution with ϫ10 water immersion objective resulted in 16-m pixel size, and the temporal resolution was 1 kHz.…”

Arrhythmias in the developing heart

“…Studies on chick embryos in vivo showed that hypoxia can accelerate maturation of the AV junction and lead to earlier appearance of mature (apex-to-base) ventricular activation patterns (Nanka et al 2008), possibly through increased apoptosis of the AV myocardium. Another player in developing proper fibrous insulation of the AV junction is the developing epicardium (Kolditz et al 2007(Kolditz et al , 2008, and perturbations of this process may lead to ventricular pre-excitation.…”