EFFECTS OF HYPERTENSION AND AGING ON FIBRONECTIN EXPRESSION IN AORTA OF DAHL SALT-SENSITIVE RATS

Effects of hypertension and aging on aortic fibronectin expression wer e investigated in male Dahl salt-sensitive (Dahl-S) and salt-resistant (Dahl-R) rats fed either a low- or high-salt diet from 5 to 37 wk of age. In comparison to low-salt controls, the steady-state mRNA levels for aortic fibronectin in salt-loaded Dahl-S rats were dramatically in creased at 37 wk of age, corresponding to a severe stage of hypertensi on with high mortality, whereas at earlier ages representing early to established phases of hypertension, no significant changes were observ ed. Salt loading affected neither blood pressure nor aortic fibronecti n expression in Dahl-R rats. Aging without coexisting hypertension did not cause significant changes in aortic fibronectin mRNA levels all t hrough the study period in either strain of rats. These results sugges t that aortic fibronectin may be strongly regulated by factors associa ted with severe hypertensive organ damages caused by long-standing hyp ertension in salt-loaded Dahl-S rats. Also suggested was that aortic f ibronectin may not play a major role in the pathogenesis of early aort ic changes occurring in response to hypertension or as a process of ag ing.