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Chronic hyperinsulinemia and blood pressure. Interaction with catecholamines?
J E Hall1, M W Brands, S D Kivlighn
1Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216-4505.
Hypertension (Dallas, Tex. : 1979)
|May 1, 1990
Summary
Chronic hyperinsulinemia in dogs did not cause hypertension or increase plasma catecholamines. This study found no evidence that insulin or its interaction with catecholamines contributes to high blood pressure in normal canines.
Area of Science:
- Endocrinology
- Cardiovascular Physiology
- Hypertension Research
Background:
- Obesity-associated hypertension is often linked to hyperinsulinemia and increased adrenergic activity.
- However, a direct causal relationship between insulin, catecholamines, and hypertension remains unestablished.
Purpose of the Study:
- To investigate if chronic hyperinsulinemia, similar to levels in obese hypertensive patients, induces hypertension in normal dogs.
- To determine if hyperinsulinemia elevates plasma catecholamines or enhances norepinephrine's blood pressure effects.
Main Methods:
- Normal dogs underwent a 7-day continuous insulin infusion to maintain euglycemia, mimicking hyperinsulinemia.
- Plasma insulin, catecholamines (norepinephrine, epinephrine), and mean arterial pressure were measured.
- A separate group received norepinephrine infusion, with and without simultaneous insulin infusion, to assess potentiating effects on blood pressure.
Main Results:
- Insulin infusion significantly increased fasting insulin levels but did not alter mean arterial pressure in normal dogs.
- Plasma norepinephrine and epinephrine levels remained unchanged during insulin infusion.
- Simultaneous insulin and norepinephrine infusion did not further elevate mean arterial pressure compared to norepinephrine alone.
Conclusions:
- Chronic hyperinsulinemia, at levels comparable to obese hypertensive individuals, does not induce hypertension in normal dogs.
- Insulin does not appear to increase plasma catecholamines or potentiate the pressor effects of norepinephrine in this model.
- These findings suggest that hyperinsulinemia alone or its interaction with catecholamines may not be a direct cause of hypertension in normal canine physiology.