This study was designed to examine the role of endogenous
opiates in the development of renovascular hypertension and in
baroreflex sensitivity in hypertensive rats. After 2 weeks mean arterial
blood pressure in morphine treated hypertensive rats was 22.3 mmHg
lower than in saline treated hypertensive rats (-14%)(P <0.01), the heart
rate was 55.7 beats higher than in saline treated hypertensive
rats(P<0.05).Morphine also depresses significantly the baroreflex
sensitivity when compared with saline hypertensive group (P<0.01).
Naloxone administration during the onset of hypertension significantly
alleviated the rise in blood pressure, the mean arterial blood pressure was
15.3 mmHg lower than saline treated hypertensive rat (4.0%)(P <0.01).
The heart rate was 116.3/minute beats higher than saline treated
hypertensive rats. It contrast naloxone significantly increase baroretlex
sensitivity when compared with saline hypertensive group (t2 04%)
(P <0.00 1) These data support a role of opiates in the pathogenesis of
renovascular hypertension which may be related to alternation in
baroreceptor reflex function
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