DIFFERENCES IN TEMPERATURE-SENSITIVE RECEPTOR-BINDING OF GLUCOCORTICOIDS IN SPONTANEOUSLY HYPERTENSIVE AND NORMOTENSIVE WISTAR-KYOTO RATS

Glucocorticoid receptor binding was compared in liver cytosol preparat ions from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats using homologous displacement of [H-3]dexamethasone. At 5 degree s C, there was no difference in receptor binding affinity or concentra tion between strains for dexamethasone, corticosterone or aldosterone. At 37 degrees C, affinity for dexamethasone was lower than at 5 degre es C for both rat strains and decreased with time. However, al this hi gher temperature, binding affinity in the SHR preparation was consiste ntly higher than in the WKY preparation. The WKY preparation had a hig her receptor concentration. The rate of dissociation of the [H-3]dexam ethasone-receptor complex prepared at 5 degrees C and then incubated a t 37 degrees C was rapid but not different between strains. A possible explanation of these results is that the relationship of the heat sho ck proteins to the receptor heterocomplex is different between strains . Evidence exists of a genetic difference in Hsp 70 between SHR and WK Y rats, although its cosegregation with blood pressure has not been es tablished.