Effect of insulin on the proliferation of cultured primate arterial smooth muscle cells.

Abstract

Smooth muscle cells were grown from thoracic aortas of 1-year-old monkeys (Macaca nemistrina). The effect of insulin on the proliferation of these cells was studied by comparing the growth of cells in culture medium to which insulin had been added with that of cells in basal (1% monkey serum) medium and in growth-promoting 5% monkey serum. Insulin in concentrations of 10, 100, 1,000, and 10,000 muunits/ml resulted in successively greater stimulation of growth which was highly significant (P smaller than 0.001) by analysis of variance. There was a significant linear relationship between the logarithm of the insulin dose and cell growth. However, the highest concentration of insulin produced only 50% of the effect of 5% monkey serum. Serum from which insulin had been removed stimulated growth less well (P smaller than 0.05) than did untreated serum at the same concentration (5%) but had significant (P smaller than 0.05) stimulating properties compared with whole serum at a lower concentration. Cells that were older in culture life (eight or nine passages) did not show a growth response to insulin and had an attenuated response to 5% serum. The effect of insulin (100 muunits/ml) was inhibited by dibutyryl cyclic adenosine monophosphate (db-cAMP) (5 times 10-5 M), although there was a latent period of 3 days before inhibition occurred; db-cAMP had no effect on cell counts in the absence of insulin. The electron microscopic appearance of the cells was unaltered by insulin.

The vasodilator action of insulin. Implications for the insulin hypothesis of hypertension.

“…First, chronic hyperinsulinemia might elevate arterial pressure, because insulin is reported to produce trophic actions on vascular muscle that could, over time, increase vascular resistance and arterial pressure. 41 However, Tsutsu et al 42 have reported that chronically elevated plasma insulin levels in patients with insulinoma did not result in increased arterial pressure. Furthermore, arterial pressure did not fall in these patients after tumor resection.…”

Insulin, renin-aldosterone system and blood pressure in obese people

“…14,18 Obese subjects are characterized by hyperinsulinemia and insulin-resistance, and these factors could be the cause of increased blood pressure. 19 Hyperinsulinemia, could indeed increase sympathetic activity 20,21 and sodium reabsorption, 22 modify ion transport 23 ± 25 and stimulate proliferation of smooth-muscle cells, 26 mechanisms which promote and maintain high blood pressure values.…”

Dietary determinants of subclinical inflammation, dyslipidemia and components of the metabolic syndrome in overweight children: a review

“…38 There are several possible mechanisms by which insulin could increase BP, including increased renal sodium absorption, 39 increased sympathetic tone 40 and hypertrophy of vascular smooth muscle increasing peripheral resistance. 41 Several studies in children and adolescents have found positive correlations between fasting insulin concentrations and SBP. 42,43 High dietary fat intake may increase insulin resistance independent of weight gain.…”