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Adrenomedullin microinjection into the area postrema increases blood pressure
M A Allen1, P M Smith, A V Ferguson
1Department of Physiology, Queen's University, Kingston, Ontario, Canada.
The American Journal of Physiology
|June 1, 1997
Summary
Adrenomedullin (ADM) injected into the area postrema (AP) significantly increases blood pressure and heart rate in rats. This study reveals a direct physiological role for ADM within the brain
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Endocrinology
Background:
- Adrenomedullin (ADM) is a vasoactive peptide found in circulation.
- Systemic ADM administration lowers blood pressure, while central administration raises it.
- ADM's influence on area postrema (AP) neurons suggests a role in cardiovascular control.
Purpose of the Study:
- To investigate the physiological significance of ADM acting within the area postrema (AP).
- To determine the direct cardiovascular effects of ADM microinjected into the AP in vivo.
Main Methods:
- Microinjection of ADM (1 and 10 microM) into the AP and nucleus of the solitary tract (NTS) of urethane-anesthetized rats.
- Measurement of blood pressure (BP) and heart rate (HR) responses.
- Analysis of BP and HR changes using area under the curve (AUC).
Main Results:
- Microinjection of 10 microM ADM into the AP caused significant, transient increases in BP and HR.
- Lower ADM concentration (1 microM) had no effect on BP or HR.
- ADM microinjections into the adjacent NTS did not affect BP or HR.
Conclusions:
- ADM acts at the area postrema (AP) to elicit significant cardiovascular responses.
- This study provides the first evidence of a physiological role for ADM within a specific brain nucleus (AP) in regulating cardiovascular function.