Cellular Mechanisms Underlying Arteriolar Myogenic Tone

The aim of the studies was to investigate the role of protein tyrosine phosphorylation in myogenic responsiveness of rat skeletal muscle arterioles. Arterioles with myogenic tone dilated in response to treatment with broad spectrum tyrosine kinase inhibitors that included genistein and tyrphostin A47 and constricted to the tyrosine phosphatase inhibitor such as pervanadate. Tyrosine kinase activity was found to alter vessel diameter and modulate of arteriolar tone. However, results indicate that acute arteriolar myogenic constriction does not itself require tyrosine phosphorylation. Tyrosine phosphorylation was found to be dissociated from the myogenic contractile response. Phosphotyrosine was found to be elevated with increasing intraluminal pressure and when the arterioles were rendered passive by superfusion with Calcium deplete buffer and suggests that the increased phosphotyrosine may be related to increased wall tension caused by the increased intraluminal pressure. Phosphotyrosine signal may be relate to growth and proliferation of smooth muscle following a sustained rise in arteriole transmural pressure.