title: Diastolic filling characteristics in the stage 12 to 27 chick embryo ventricle.
abstract: Cardiac output is affected by the diastolic filling characteristics of the ventricle. We hypothesized that the relative contributions of passive and active filling change as the ventricle develops from a smooth-walled tube to a trabeculated four-chamber heart. In stage 12 to 27 white Leghorn chick embryos, we simultaneously measured ventricular pressure with a servo-null micropressure system and dorsal aortic and atrioventricular velocities with a 20-MHz pulsed-Doppler velocity meter. The analog waveforms were sampled at 500 Hz and converted to digital format via an analog/digital board. We partitioned diastole into passive and active components. The passive phase began with the return of the pressure curve to baseline and extended to the onset of the a-wave. The active phase began with the upstroke of the atrial velocity curve and extended to the upstroke of the ventricular pressure curve at end-diastole. Data are presented as mean +/- SEM (n greater than or equal to 6 at each stage) and analyzed by analysis of variance and regression analysis. At similar cycle lengths ranging from 480 to 600 ms (p greater than 0.05), end-diastolic pressure increased from 0.24 +/- 0.02 mm Hg at stage 12 to 0.55 +/- 0.01 mm Hg at stage 27. Passive and active filling volumes were 92 (0.0038 +/- 0.0005 mm3) and 8% (0.0004 +/- 0.0002 mm3), respectively, at stage 12 and changed to 24 (0.23 +/- 0.08 mm3) and 76% (0.62 +/- 0.08 mm3), respectively, at stage 27. The ratio of passive to active filling volume decreased from 7.89 to 0.35.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Cook Research Laboratory, Department of Pediatrics, University of Rochester School of Medicine and Dentistry, New York 14642.
authors.forename: N
authors.initials: N
authors.lastname: Hu
authors.forename: D M
authors.initials: DM
authors.lastname: Connuck
authors.forename: B B
authors.initials: BB
authors.lastname: Keller
authors.forename: E B
authors.initials: EB
authors.lastname: Clark
mesh_terms: D000818:Animals; D002642:Chick Embryo; D003971:Diastole / Q000502:physiology; D006321:Heart / Q000196:embryology* / Q000502:physiology; D013997:Time Factors; D016276:Ventricular Function / Q000502:physiology