[Effects of alpha 1-adrenergic receptor subtypes activation on proliferation of smooth muscle cells in rabbit aorta].

The effect of alpha 1-Adrenoceptor (alpha 1-AR) and its subtypes, alpha 1A and alpha 1B, activation on the proliferation of cultured vascular smooth muscle cells (VSMC) was studied by [3H]-thymidine (3H-TdR) incorporation and in situ hybridization. Norepinephrine (NE) promotes DNA synthesis of VSMC. The action was induced by activation of alpha 1A-AR subtype and increase of c-fos gene expression. However, the DNA synthesis was inhibited by activation of alpha 1B-AR subtype. There was a synergetic effect on VSMC DNA synthesis between NE and neuropeptide Y (NPY). But only additional effect was found between NE and Ang II. More over, it was found that alpha 1B-AR subtype showed significant constitutive inhibitory effect of VSMC DNA synthesis.