Early events in development of electrical activity and contraction in embryonic rat heart assessed by optical recording.

Hirota, Akihiko; Kamino, Kohtaro; Komuro, Hitoshi; Sakai, Tetsuro; Yada, Toshihiko

doi:10.1113/jphysiol.1985.sp015897

Cited by 64 publications

(49 citation statements)

References 31 publications

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“…The first movements of erythroblasts correlate temporally with the formation of a beating heart tube and linkage of embryonic and yolk sac vascular systems. 3,7,20,21,57 These data are consistent with reports of the first erythroblasts entering the allantoic vasculature (contiguous with the distal end of the aortae) at 6 to 10 sp. 22 At E8.5 to E9.0 (8-15 sp), we found evidence of increased flow as red blood cells penetrated further into the embryo proper arterial system.…”

Section: Onset Of Circulationsupporting

confidence: 81%

“…The transition to a looped peristaltic beating heart occurs by 8 sp. 7,20,21 Increasing circulation within the embryo proper does not achieve a steady-state density of red blood cells until E10…”

Section: Changes In Distribution Of Red Blood Cells Are Precisely Temmentioning

confidence: 99%

“…This is thought to occur at E8.5 (8-10 somite pairs [sp]). 7,8 More recently, unpublished results have been used to contend that hematopoietic progenitors "freely circulate between extra-and intra-embryonic compartments" as early as E8.25 or 5 sp. 9 In contrast, we found that definitive hematopoietic progenitors remain almost entirely restricted to the yolk sac as late as E9.25.…”

Section: Introductionmentioning

confidence: 99%

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Circulation is established in a stepwise pattern in the mammalian embryo

McGrath

Koniski

Malik

et al. 2003

Blood

254

217

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To better understand the relationship between the embryonic hematopoietic and vascular systems, we investigated the establishment of circulation in mouse embryos by examining the redistribution of yolk sac-derived primitive erythroblasts and definitive hematopoietic progenitors. Our studies revealed that small numbers of erythroblasts first enter the embryo proper at 4 to 8 somite pairs (sp) (embryonic day 8.25 [E8.25]), concomitant with the proposed onset of cardiac function. Hours later (E8.5), most red cells remained in the yolk sac. Although the number of red cells expanded rapidly in the embryo proper, a steady state of approximately 40% red cells was not reached until 26 to 30 sp (E10). Additionally, erythroblasts were unevenly distributed within the embryo's vasculature before 35 sp. These data suggest that fully functional circulation is established after E10. This timing correlated with vascular remodeling, suggesting that vessel arborization, smooth muscle recruitment, or both are required. We also examined the distribution of committed hematopoietic progenitors during early embryogenesis. Before E8.0, all progenitors were found in the yolk sac. When normalized to circulating erythroblasts, there was a significant enrichment (20-to 5-fold) of progenitors in the yolk sac compared with the embryo proper from E9.5 to E10.5. These results indicated that the yolk sac vascular network remains a site of progenitor production and preferential adhesion even as the fetal liver becomes a hematopoietic organ. We conclude that a functional vascular system develops gradually and that specialized vascular-hematopoietic environments exist after circulation becomes fully established. IntroductionA functional circulatory system is an early requirement for survival and growth of the mammalian embryo and is the first organ system to develop in the embryo. 1 The circulatory system is composed of vascular, hematopoietic, and cardiac components, each formed from discrete regions of mesoderm. The first endothelial cells and blood cells are generated in yolk sac blood islands beginning at embryonic day 7 (E7.0) in the mouse. By E8.0, thousands of nucleated primitive red blood cells have formed within a vascular plexus in the yolk sac. [2][3][4] Concurrently, the aorta and the peristaltic beating heart tube form in the embryo proper. In the next 36 hours, there is a remarkable increase in complexity of vascular and hematopoietic systems. The vascular plexus remodels and expands into an arborized network of specialized arteries and veins. Primitive erythroblasts from the yolk sac continue to divide and mature, and a second wave of hematopoiesis creating definitive (adultlike) progenitors originates in the yolk sac. 5,6 Thus, the early vascular system is the hematopoietic environment for primitive and definitive lineages until the specialized stromal microenvironment of the fetal liver (beginning E10), and later the adult bone marrow, is available. However, the nature of any specific interactions between early embryonic hematopo...

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Section: Onset Of Circulationsupporting

confidence: 81%

Section: Changes In Distribution Of Red Blood Cells Are Precisely Temmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Circulation is established in a stepwise pattern in the mammalian embryo

McGrath

Koniski

Malik

et al. 2003

Blood

254

217

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“…This is in large part because of technical challenges associated with studying these small, delicate, and spatially highly complex structures. The site of the first pacemaking activity has been localized to the left sinus horn in embryonic chick (23) and rat heart (17). Studies focused primarily on ventricular conduction depicted the activation of the atria proper from their upper right portion, proceeding toward the left side and the atrioventricular junction in both embryonic chick (32,35) and rabbit (34) heart.…”

mentioning

confidence: 99%

Changes in activation sequence of embryonic chick atria correlate with developing myocardial architecture

Sedmera

Wessels²,

Trusk³

et al. 2006

American Journal of Physiology-Heart and Circulatory Physiology

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Changes in activation sequence of embryonic chick atria correlate with developing myocardial architecture. Am J Physiol Heart Circ Physiol 291: H1646 -H1652, 2006. First published May 5, 2006 doi:10.1152/ajpheart.01007.2005.-To characterize developmental changes in impulse propagation within atrial musculature, we performed high-speed optical mapping of activation sequence of the developing chick atria using voltage-sensitive dye. The activation maps were correlated with detailed morphological studies using scanning electron microscopy, histology, and whole mount confocal imaging with three-dimensional reconstruction. A preferential pathway appeared during development within the roof of the atria, transmitting the impulse rapidly from the right-sided sinoatrial node to the left atrium. The morphological substrate of this pathway, the bundle of Bachman, apparent from stage 29 onward, was a prominent ridge of pectinate muscles continuous with the terminal crest. Further acceleration of impulse propagation was noted along the ridges formed by the developing pectinate muscles, ramifying from the terminal crest toward the atrioventricular groove. In contrast, when the impulse reached the interatrial septum, slowing was often observed, suggesting that the septum acts as a barrier or sink for electrical current. We conclude that these inhomogeneities in atrial impulse propagation are consistent with existence of a specialized network of fast-conducting tissues. The purpose of these preferential pathways appears to be to assure synchronous atrial activation and contraction rather than rapid impulse conduction between the sinoatrial and atrioventricular nodes. chick embryo; optical mapping; conduction system; internodal pathways; pectinate muscles THE SPECIALIZED CONDUCTION tissues mediate coordinated propagation of electrical activity through the adult vertebrate heart. Although the ventricular component of the conduction system (His bundle, bundle branches, and Purkinje fibers) is relatively well characterized (reviewed in Ref. 14), controversy persists about the existence and even definition of specialized fastconducting tissues within the atria (21). Inhomogeneities in conduction properties of atrial tissues are widely recognized and are believed to be largely due to structural characteristics (18). The morphological substrate of so-called internodal conduction tracts (20) is less well defined, since these bundles do not satisfy the criteria set for specialized ventricular conduction tissues (1).Atrial conduction in adult human and animal hearts is well studied. Excitation starts in the sinoatrial node (or sinus venosus in the lower vertebrates) and propagates across the atrial roof in a generally radial manner, described as "waves produced when a stone is dropped into still water" (26). These "waves" are not perfectly concentric, since there are numerous "holes" in the atria where the veins enter (21), and spread of impulse appears to be faster along the main bundles of the pectinate muscles (2, 10, 26). In particu...

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“…Furthermore, optical techniques can facilitate the simultaneous recording of cellular electrical events from many adjacent sites in a preparation (for reviews see Salzberg, 1983;Cohen & Lesher, 1986;Grinvald, Frostig, Lieke & Hildesheim, 1988;Kamino, 1990Kamino, , 1991. We have introduced optical recording techniques to monitor electrical activity from early developing embryonic systems, such as hearts (Hirota, Kamino, Komuro, Sakai & Yada, 1985;Hirota, Kamino, Komuro & Sakai, 1987;Kamino, Komuro, Sakai & Hirota, 1988; and for reviews see Kamino, Hirota & Komuro, 1989a;Kamino, 1990Kamino, , 1991, ganglia (Sakai, Hirota, Komuro, Fujii & Kamino, 1985;, and brain stems (Kamino, Katoh, Komuro & Sato, 1989b;Kamino, Komuro, Sakai & Sato, 1990).…”

Section: Introductionmentioning

confidence: 99%

Optical determination of impulse conduction velocity during development of embryonic chick cervical vagus nerve bundles.

Sakai

Komuro

Kato

et al. 1991

The Journal of Physiology

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SUMMARY1. Employing an optical method for multiple-site simultaneous recording of electrical activity, we have determined the conduction velocity in cervical vagus nerve bundles isolated from 5-to 21-day-old chick embryos, and investigated its developmental changes.2. The preparations were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761), and action potential-(impulse-) related optical signals were elicited by brief stimuli applied to the end of the vagus nerve bundle with a suction electrode. Optical signals were recorded simultaneously from many contiguous regions using a 12 x 12-element photodiode array.3. The optical signals spread with small delay from the site of stimulation. From the relationship between the delay and distance from the current-applying electrode, conduction velocities were estimated in each tested preparation: the conduction velocity was very small and increased monotonically from about 0-1 m s-1 at 5 days embryonic age to about 0-4 m s-' by hatching. The increase in the conduction velocity was closely related to a developmental increase in the diameter of the vagus nerve bundle.4. In addition, we have examined the spread of electrotonic potentials. The space constant was very small (200-450 ,um) and increased as development proceeded.5. Compound optical action signals having two distinct components were also recorded. They often appeared to be concentrated in the preparations from 8-to 12-day-old embryos. The conduction velocity of the second component was slower than that of the first. We suggest that appearance of the second component reflects degeneration of a subset of axons resulting from 'neural cell death' during the development of the vagus nerve.

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Early events in development of electrical activity and contraction in embryonic rat heart assessed by optical recording.

Cited by 64 publications

References 31 publications

Circulation is established in a stepwise pattern in the mammalian embryo

Circulation is established in a stepwise pattern in the mammalian embryo

Changes in activation sequence of embryonic chick atria correlate with developing myocardial architecture

Optical determination of impulse conduction velocity during development of embryonic chick cervical vagus nerve bundles.

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