A physico-chemical comparison of aortic receptors in rat hypertension models

Rat models of genetic hypertension include spontaneous hypertension and resistance or sensitivity to mineralocorticoid and salt induced hypertension. Previously, altered aldosterone binding to corticoid receptor I was found in aortic smooth muscle cells cultured from Fischer 344 rats which are extremely resistant to steroid and salt induced hypertension. The corticoid receptor I of Fisher 344 rats had a lower affinity than that of salt sensitive Wistar-Kyoto controls, as well as spontaneously hypertensive rats and Sprague-Dawley rats. In the present study, we have used DEAE-cellulose ion exchange chromatography to compare the structure (charge properties) and steroid specificity of vascular corticoid receptor I and II sites in these same rat hypertension models. No variations in ion exchange properties of type I and II receptors were found. Together with the lower aldosterone affinity of corticoid receptor I sites in Fischer 344 rats these data suggest an altered binding domain which is not seen as a difference in charge density of the receptor protein by ion exchange chromatography.