September 1, 1995American Journal of Hypertension
Insulin induces medial hypertrophy of myocardial arterioles in rats
Key result
Intraperitoneal insulin administration for 3 weeks induced medial hypertrophy of myocardial arterioles in rats, regardless of changes in blood pressure or heart weight.
Why the study?
Does insulin administration induce arteriolar hypertrophy, myocardial hypertrophy, and blood pressure changes in SHR and WKY rats?
Population
SHR and WKY rats
Comparison
Insulin administered intraperitoneally for 3… vs Control rats not receiving insulin
Design
Preclinical
Follow-up
3 weeks
Authors
Discussion
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Implication
Hyperinsulinemia may promote arteriolar remodeling independent of BP or cardiac mass in rats; hypothesis-generating for human hypertension, requires clinical validation.
Key Points
- To determine whether hyperinsulinemia promotes myocardial arteriolar hypertrophy, cardiac enlargement, and elevated blood pressure independently of hyperglycemia.
- Administered intraperitoneal insulin for 3 consecutive weeks to spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats.
- Provided 10% sugar drinking water to prevent hypoglycemia and 8% dietary salt chow to accentuate blood pressure.
- Measured blood pressure via tail-cuff, assessed heart-to-body weight ratios, and calculated wall thickness relative to lumen diameter in ~100-micron myocardial arterioles.
- Blood pressure and heart weight increased after 3 weeks in SHR but showed no increase in normotensive WKY rats.
- Arteriolar wall thickness increased significantly in all insulin-treated rats via medial hypertrophy without atherosclerosis, regardless of blood pressure elevation or heart weight changes.
- Blood glucose elevations occurred across all groups, indicating that medial hypertrophy resulted directly from hyperinsulinemia rather than hyperglycemia.
Structured PICO
Does insulin administration induce arteriolar hypertrophy, myocardial hypertrophy, and blood pressure changes in SHR and WKY rats?
P
Population
SHR and WKY rats administered insulin for 3 consecutive weeks to investigate the effect of hyperinsulinemia.
I
Intervention
Insulin administered intraperitoneally for 3 consecutive weeks (with 10% sugar in drinking water and 8% table salt in chow)
C
Comparator
Control rats not receiving insulin
O
Outcome
Vascular wall thickness factored with lumen diameter (arteriolar hypertrophy), heart weights factored with body weights (myocardial hypertrophy), and blood pressuresurrogate
Hyperinsulinemia is associated with hypertrophy of the media of arterioles regardless of the increase in heart weight or the rise in blood pressure in a rat model.
Cite This Study
Zimlichman et al. (1995) studied Hyperinsulinemia and arteriolar hypertrophy. Insulin vs. No insulin (implied) was evaluated on Vascular wall thickness factored with lumen diameter (arteriolar hypertrophy). Intraperitoneal insulin administration for 3 weeks induced medial hypertrophy of myocardial arterioles in rats, regardless of changes in blood pressure or heart weight.