title: Heart rate perturbation in the stage 17-27 chick embryo: effect on stroke volume and aortic flow.
abstract: Heart rate (HR), stroke volume (SV), and aortic flow increase linearly between developmental stages 17 and 27, as the embryonic chick heart progresses from a bent tube to a rudimentary four-chambered structure and cardiac mass increases fourfold. We hypothesized that HR perturbation, expressed as percent of intrinsic HR (%HR), would have a developmentally dependent effect on flow and SV. HR was transiently perturbed to 40-250% of intrinsic rate with a 1-mm cooled or heated steel probe applied to the sinus venosus of 81 embryos. Aortic blood velocity, cross-sectional area, and HR were used to calculate flow and SV. At each stage, flow was maximal at intrinsic HR. The %HR vs. SV relationship was linear, inverse, and developmentally dependent. In spite of a tremendous change in ventricular shape, mass, and volume, HR control during development of the preinnervated heart maximizes blood flow to the developing embryo.
authors.affiliation: Division of Cardiology, Children's Memorial Hospital, Chicago, Illinois 60611.
authors.forename: B
authors.initials: B
authors.lastname: Cuneo
authors.forename: S
authors.initials: S
authors.lastname: Hughes
authors.forename: D W
authors.initials: DW
authors.lastname: Benson
mesh_terms: D000818:Animals; D001011:Aorta / Q000196:embryology / Q000502:physiology; D001783:Blood Flow Velocity; D002642:Chick Embryo; D006321:Heart / Q000196:embryology* / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors