COMPARISON OF CHANGES IN BLOOD-PRESSURE AND DIPSOGENIC RESPONSIVENESSTO ANGIOTENSIN-II IN MALE AND FEMALE RATS CHRONICALLY EXPOSED TO COLD

In most forms of experimentally induced hypertension in rats, females develop a less severe form of the disease than males. The objective of the present study was to compare the two genders with respect to the development of cold-induced hypertension. The results of the study ind icate that both males and females develop comparable elevations of blo od pressure and at approximately the same rate. Thus, the blood pressu res of both groups increased significantly within 2 weeks of exposure to cold and reached similar maximal levels by the seventh week. The di psogenic responsiveness of both groups of cold-exposed rats to acute a dministration of the peptide hormone, angiotensin II (AngII), was incr eased to approximately the same extent above that of warm-adapted coun terparts, suggesting an increase in the responsiveness to AngII in the brain. To assess this possibility, the induction of the oncogene, cFo s, was studied in brain following IV infusion of AngII (333 ng/kg/min) . Fos-like immunoreactivity (FLI) was greater (p < 0.01) in subfornica l organ, supraoptic and paraventricular hypothalamic nuclei of both co ld-exposed groups compared to warm-adapted controls. Thus, both male a nd female rats have similar elevations of blood pressure as well as in creased dipsogenic and FLI responsiveness to administration of AngII d uring chronic exposure to cold. Copyright (C) 1996 Elsevier Science In c.