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document
Acute pressor and hormonal effects of beta-endorphin at high doses in healthy and hypertensive subjects : role of opioid receptor agonism . CONTEXT The opioid system is involved in blood pressure regulation in both normal humans and patients with essential hypertension . OBJECTIVE The objective of the study was to investigate the effects of a high-dose infusion of beta-endorphin , an opioid peptide , on blood pressure and on the hormonal profile in healthy subjects and in hypertensive patients and the mediation played by opioid receptor agonism . DESIGN , SETTING , AND PARTICIPANTS According to a randomized double-blind design , 11 healthy subjects ( controls ) and 12 hypertensive inpatients ( mean age , 38.9 and 40.4 yr , respectively ) received 1-h iv infusion of beta-endorphin ( 250 mug/h ) and , on another occasion , the same infusion protocol preceded by the opioid antagonist naloxone ( 8 mg ) . MAIN OUTCOME MEASURES Hemodynamic and hormonal measurements were performed at established times during the infusion protocols . RESULTS At baseline , circulating beta-endorphin , norepinephrine , and endothelin-1 in hypertensive patients were significantly ( P < 0.05 ) higher than in controls . In controls , beta-endorphin reduced blood pressure ( P < 0.01 ) and circulating norepinephrine ( P < 0.02 ) and increased plasma atrial natriuretic factor ( P < 0.003 ) and GH ( P < 0.0001 ) . In hypertensive patients , beta-endorphin decreased systemic vascular resistance ( P < 0.0001 ) , blood pressure ( P < 0.0001 ) , and plasma norepinephrine ( P < 0.0001 ) and endothelin-1 ( P < 0.0001 ) and raised circulating atrial natriuretic factor ( P < 0.0001 ) , GH ( P < 0.0001 ) , and IGF-I ( P < 0.0001 ) . These hemodynamic and hormonal responses to beta-endorphin in hypertensive patients were significantly ( P < 0.0001 ) greater than in controls but were annulled in all individuals when naloxone preceded beta-endorphin infusion . CONCLUSIONS High doses of beta-endorphin induce hypotensive and beneficial hormonal effects in humans , which are enhanced in essential hypertension and are mediated by opioid receptors .
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Intervention_Pharmacological
beta-endorphin
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Intervention_Pharmacological
beta-endorphin
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Intervention_Pharmacological
1-h iv infusion of beta-endorphin ( 250 mug/h )
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Intervention_Pharmacological
opioid antagonist naloxone ( 8 mg )
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Intervention_Pharmacological
beta-endorphin
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Intervention_Pharmacological
beta-endorphin
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Outcome_Physical
Hemodynamic and hormonal measurements
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Outcome_Physical
circulating beta-endorphin , norepinephrine , and endothelin-1
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Outcome_Physical
blood pressure
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Outcome_Physical
circulating norepinephrine
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Outcome_Physical
plasma atrial natriuretic factor
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Outcome_Physical
systemic vascular resistance
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Outcome_Physical
blood pressure
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Outcome_Physical
plasma norepinephrine
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Outcome_Physical
endothelin-1
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Outcome_Physical
circulating atrial natriuretic factor
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Outcome_Physical
GH
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Outcome_Physical
IGF-I
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Outcome_Physical
hemodynamic and hormonal responses
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Participant_Condition
healthy and hypertensive
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Participant_Condition
normal
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Participant_Condition
essential hypertension
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Participant_Sample-size
11
22279
Participant_Sample-size
12
22280
Participant_Age
38.9
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Participant_Age
40.4