Figure 3.

Arterial blood pressure traces and calculated heart rate in a Day 21 chicken embryo before and after injection of the hypertensive agent, angiotensin II. Blood pressure was measured in a chronically indwelling cannula that had been implanted in a CAM artery by keyhole surgery through a small hole in the eggshell. CAM arterial blood pressure, assumed to be a proxy for systemic embryonic pressure, increased dramatically within less than a minute after injection, and stayed elevated for at least 15 min. Heart rate was largely unchanged. These data indicate that receptors for ang II are present at hatching, typically occurring on Day 21 post-fertilization. Modified from [83].