Captopril and stress-induced hypertension in the borderline hypertensive rat.
OBJECTIVE
Daily exposure to air-jet stress (AJS) causes sustained elevations of blood pressure in borderline hypertensive rats (BHR). It is known that the renin-angiotensin system is activated during episodes of behavioral stress, and the purpose of this study was to assess the involvement of renin-angiotensin system in the development of stress-induced hypertension in the BHR.


METHODS
Four groups of 8- and 9-week-old rats were studied: they received, respectively, oral captopril and AJS; oral captopril without AJS; AJS without captopril; and neither AJS nor captopril.


METHODS
After 10 days of AJS and captopril conditions, femoral and jugular catheters were implanted for the measurement of mean arterial pressure and pressor responses to norepinephrine and tyramine. Blood samples were collected for the measurement of norepinephrine and plasma renin activity.


RESULTS
Ten days of AJS caused a significant elevation of blood pressure in BHR exposed to AJS without receiving captopril but not in those animals given captopril concurrently with AJS. Circulating norepinephrine and blood pressure responses to exogenous norepinephrine and tyramine were similar across the four groups. Plasma renin activity was highest in BHR given captopril, and was significantly elevated during an acute episode of AJS.


CONCLUSIONS
The renin-angiotensin system may be important in the development of stress-induced hypertension in the BHR.
Coste
S C
SC
Department of Medical Psychology, Oregon Health Sciences University, Portland 97201-3098, USA.
Qi
Y
Y
Brooks
V L
VL
McCarron
D A
DA
Hatton
D C
DC
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology*; D005260:Female; D006824:Hybridization, Genetic; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D008297:Male; D009638:Norepinephrine / Q000097:blood / Q000494:pharmacology; D010812:Physical Stimulation; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012083:Renin / Q000097:blood; D013312:Stress, Physiological / Q000150:complications*; D014439:Tyramine / Q000494:pharmacology
D002216:Captopril; D012083:Renin; D009638:Norepinephrine; D014439:Tyramine