Insulin induces medial hypertrophy of myocardial arterioles in rats

Abstract

To investigate the effect of hyperinsulinemia on arteriolar hypertrophy, myocardial hypertrophy, and blood pressure, we administered insulin intraperitoneally to SHR and WKY rats for 3 consecutive weeks. To prevent hypoglycemia, the drinking water contained 10% sugar, and to accentuate the blood pressure, their chow contained 8% table salt. Blood pressure was measured by the tail-cuff method. Heart weights were factored with body weights. Arterioles of approximately 100 microns in diameter were examined at the end of the experiment and the vascular wall thickness was factored with the lumen diameter. At the end of 3 weeks, blood pressure rose in the SHR but not in the WKY rats. The heart weights in the WKY normotensive rats did not increase, whereas in the SHR they did. Furthermore, there was a significant rise in vessel wall thickness in the rats that received insulin, whether there was a rise in blood pressure or not and whether they had an increase in heart weight or not. There was a similar rise in blood glucose in all the groups, with slightly more accentuated rise in the SHR that received insulin. Nevertheless the increase in vascular wall thickness occurred only in the groups which received insulin. This seems to preclude the importance of hyperglycemia per se as the causative agent for the increase in vascular wall thickness in this study. The increase was in the form of medial hypertrophy without any sign of atherosclerosis. It seems, therefore, that hyperinsulinemia is associated with hypertrophy of the media of arterioles regardless of the increase in heart weight or the rise in blood pressure.

ACC/AHA 2005 Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult

“…Some antihypertensive agents should be avoided in patients with HF because of their ability to depress cardiac function or to lead to salt and water retention. In addition, HF itself is associated with resistance to the actions of insulin (567,568), and the resulting hyperinsulinemia may promote both cardiac and vascular hypertrophy (569)(570)(571) and thus may hasten the progression of HF. These mechanisms may compound the deleterious effects of accelerated atherosclerosis and altered energy metabolism on cardiac function and may help to explain why diabetic patients with HF have a worse prognosis than their nondiabetic counterparts (75).…”

Relationship between body adiposity and arterial stiffness in young Indian adults

“…(3) Hyperinsulinemia increases the mitogenic activities that lead to vascular smooth muscle proliferation, increased collagen synthesis in the vascular wall and vascular hypertrophy. [28][29][30] In addition, adiponectin, a protein derived from adipocytes, acts as a modulator for vascular smooth muscle proliferation. [31] An increase in other inflammatory adipocytokines such as tumor necrosis factor-α, interlekin-6, leptin, plasminogen activator inhibitor-1, angiotensinogen, resistin, and C-reactive protein (CRP) also have negative impacts on vascular structure.…”

Relation of Drinking Alcohol to Atherosclerotic Risk in Type 2 Diabetes

“…Hyperinsulinemia induces proliferation of vascular smooth muscle, and this is suggested to be an early process of atherosclerosis (27). Moreover, hyperinsulinemia is associated with medial hypertrophy of myocardial arterioles (28). An inverse relationship between alcohol consumption and insulin concentrations has been reported in people with type 2 diabetes (29) as well as in nondiabetic people (30).…”