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Catecholamine responses to histamine infusion in man.
R R Schellenberg1, H Ohtaka, H B Paddon
1University of British Columbia Pulmonary Research Laboratory, Vancouver, Canada.
The Journal of Allergy and Clinical Immunology
|February 1, 1991
Summary
Histamine infusion significantly increases plasma norepinephrine levels, primarily through neural release, unlike nitroglycerin. This suggests neural norepinephrine plays a key role in histamine
Area of Science:
- Cardiovascular Physiology
- Neuropharmacology
Background:
- Histamine is known to affect blood pressure and heart rate.
- The precise mechanisms of histamine's cardiovascular effects, particularly regarding catecholamine release, require further elucidation.
Purpose of the Study:
- To compare the effects of histamine and nitroglycerin on plasma catecholamine levels during induced hypotension.
- To investigate the source of catecholamine release (neural vs. adrenal) in response to histamine.
Main Methods:
- Eight healthy men underwent incremental histamine infusions in a 30-degree tilt position, monitoring blood pressure and heart rate.
- Plasma catecholamine (norepinephrine and epinephrine) levels were measured during histamine infusion and compared to measurements during nitroglycerin-induced hypotension.
- Dose escalation continued until mean blood pressure decreased by >15 mm Hg or a maximum histamine dose was reached.
Main Results:
- Histamine caused significantly greater increases in heart rate and plasma norepinephrine (NE) compared to nitroglycerin for similar blood pressure reductions.
- Histamine infusion led to a two- to fivefold increase in NE levels, with minimal changes in epinephrine.
- Data indicate selective NE release from adrenergic nerve terminals, with limited adrenal catecholamine involvement.
Conclusions:
- Histamine selectively stimulates norepinephrine release from sympathetic nerve endings.
- Neural norepinephrine release is a significant contributor to the cardiac effects observed during histamine administration.
- This finding clarifies the role of the sympathetic nervous system in mediating histamine's cardiovascular actions.
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