Myosin heavy‐chain isoforms in adult and developing rabbit vascular smooth muscle

Abstract

Two monoclonal antibodies specific for smooth muscle myosin (designated SM‐E7 and SM‐A9) and one monoclonal anti‐(human platelet myosin) antibody (designated NM‐G2) have been used to study myosin heavy chain composition of smooth muscle cells in adult and in developing rabbit aorta. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis and Western blotting experiments revealed that adult aortic muscle consisted of two myosin heavy chains (MCH) of smooth muscle type, named MHC‐1 (205 kDa), and MHC‐2 (200 kDa). In the fetal/neonatal stage of development, vascular smooth muscle was found to contain only MHC‐1 but not MHC‐2. Non‐muscle myosin heavy chain, which showed the same electrophoretic mobility as the slower migrating MHC, was expressed in an inverse manner with respect to MHC‐2, i.e. it was detectable only in the early stages of development. The distinct pattern of smooth and non‐muscle myosin isoform expression during development may be related to the different functional properties of smooth muscle cells during vascular myogenesis. Copyright © 1989, Wiley Blackwell. All rights reserved