Abstract 131 Poster Session II, Sunday, 5/2 (poster 261)

There is a direct relationship between morphologic structure and physiologic function in the early cardiovascular development. Zebrafish provides a unique genetic model system that includes normal and abnormal cardiovascular system. We define the cardiovascular physiology of the developing heart and vasculature during primary cardiovascular morphogenesis of the normal larval zebrafish. We measured larval wet weight, ventricular and dorsal aortic pressure of a 24-hr post-hatching zebrafish with a servonull system. Analog waveforms were sampled at 500 Hz. Cycle length was measured as the time between consecutive pressure waveforms. Data (n≥4) are reported as mean±SEM, and analyzed by paired t test. Wet larva weighted 0.89±0.04 mg with cycle length (437±21 ms) remained relatively constant throughout the pressure measurement (p>0.05). The ventricular pressure had a systolic component (0.40±0.06 mmHg) and two-component diastolic phase consisting of an early diastolic slow pressure rise and end-diastolic accentuation (0.07±0.02 mmHg). Dorsal aortic pressure had a distinct systolic (0.32±0.08 mmHg) and diastolic (0.18±0.04 mmHg) portion, and contained a dicrotic notch consistent with wave reflection. The physiology of the early developing zebrafish cardiovascular system is comparable to that in other vertebrates. These techniques will allow us to study the early development of the cardiovascular system during the critical period of cardiac morphogenesis. (Figure)

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