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ACTH-induced hypertension in rats: fact or artifact?
K A Gruber1, S L Eskridge-Sloop, J C Eldridge
1Department of Medicine, Wake Forest University Medical Center, Winston-Salem, North Carolina 27103.
The American Journal of Physiology
|June 1, 1989
Summary
Adrenocorticotropic hormone (ACTH) treatment in rats did not cause hypertension when measured directly. Indirect tail-cuff methods may overestimate blood pressure changes, potentially due to stress responses.
Area of Science:
- Endocrinology
- Cardiovascular Physiology
- Renal Physiology
Background:
- Previous studies indicated adrenocorticotropic hormone (ACTH) induces hypertension in rats within 5 days.
- These studies relied on indirect tail-cuff measurements, which are acute and less precise.
- The validity of ACTH-induced hypertension using indirect methods needed further investigation.
Purpose of the Study:
- To investigate the direct cardiovascular effects of chronic ACTH administration in rats.
- To compare direct 24-hour arterial pressure measurements with indirect tail-cuff readings.
- To assess the impact of ACTH on heart rate and blood pressure variability.
Main Methods:
- Chronic administration of ACTH via subcutaneous depot injection (5 or 10 U/day for 9 days) in rats.
- Utilized chronically instrumented rats in metabolic cages for direct 24-hour mean arterial pressure monitoring.
- Included tail-cuff measurements for comparative analysis and assessment of heart rate and coefficient of variation.
Main Results:
- Tail-cuff measurements suggested hypertension, but direct 24-hour mean arterial pressure measurements did not confirm this.
- ACTH administration did not affect 24-hour heart rate or the coefficient of variation of measured parameters.
- A diuretic effect was observed, confirming ACTH bioavailability and renal effects.
Conclusions:
- Chronic ACTH treatment in rats does not induce a true hypertensive state when measured directly.
- Indirect tail-cuff measurements may overestimate blood pressure in ACTH-treated rats, possibly due to heightened cardiovascular responses to measurement stress.
- ACTH's effects on blood pressure regulation require further investigation using more direct and chronic measurement techniques.
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