Cardiovascular changes in calcium-deficient chick embryos.

We have developed an experimental system involving calcium-deficient chick embryos to examine the relationship between calcium homeostasis and cardiovascular activities. We have found that the calcium-deficient embryos, when compared with control animals, exhibit tachycardia and are significantly hypertensive. The effects are unlikely to be due to gross cardiac malformations or hypertrophy. The hypertensive condition appears to be a specific result of the systemic calcium deficiency since calcium supplementation to these embryos significantly restores the functions to normality.