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Experimental studies on cardiovascular disorders and cellular Ca handling in shell-less chick embryos
Clinical and Experimental Pharmacology & Physiology. Supplement
|January 1, 1992
Summary
Shell-less chick embryos exhibit hypertension and altered calcium handling. These findings highlight a novel experimental model for studying calcium homeostasis and hypertension development.
Area of Science:
- Cardiovascular Physiology
- Developmental Biology
- Calcium Homeostasis
Background:
- Chick embryos cultured outside the eggshell (shell-less, SL) develop hypertension and tachycardia.
- Calcium deficiency is implicated in the cardiovascular changes observed in SL embryos.
Purpose of the Study:
- To characterize the hypertension in SL chick embryos.
- To compare cardiovascular responses to adrenergic drugs and cellular calcium handling in SL and normal (NL) embryos.
Main Methods:
- Measurement of blood pressure and pulse rate before and after administration of adrenergic drugs (noradrenaline, phentolamine, isoproterenol, propranolol).
- Analysis of serum calcium levels and myocardial calcium content.
- Study of red blood cell (RBC) calcium handling, including 45Ca uptake and cell volume regulation under varying conditions.
Main Results:
- SL embryos displayed higher baseline blood pressure and increased sensitivity to noradrenaline and phentolamine.
- Serum calcium was lower in SL embryos, but myocardial calcium content was unchanged.
- SL RBCs exhibited greater ion permeability, enhanced Na-Ca exchange function, and increased calcium extrusion capacity.
Conclusions:
- The SL chick embryo presents a unique model for investigating the link between calcium homeostasis and hypertension.
- Altered cellular calcium handling mechanisms contribute to the hypertensive phenotype in SL embryos.