Insulin enhances angiotensin II induced DNA synthesis in vascular smooth muscle cells of the rat.

Hypertension has a high prevalence among subjects with decreased insulin sensitivity and/or hyperinsulinemia. Furthermore, angiotensin II plays a pivotal role in the regulation of vascular tone and is known to induce hypertrophy and/or hyperplasia in vascular smooth muscle cells. In the present study, the effect of insulin on angiotensin II induced smooth muscle cell growth (Wistar-Kyoto rat) was investigated. Cell growth was assessed by the measurement of [3H]thymidine incorporation into cell DNA. Insulin in a concentration range of 1.7 x 10(-10)-1.7 x 10(-6) M lacked any effect on cell DNA synthesis. However, insulin enhanced the angiotensin II induced DNA synthesis in a concentration-dependent manner. This effect was similar in cells with a weak and in cells with a marked response in DNA synthesis to stimulation with 100 nM angiotensin II. In conclusion, insulin is able to enhance angiotensin II induced DNA synthesis and may therefore function as a growth cofactor in vascular smooth muscle cells.