INCREASED PRESSURE INDUCES SUSTAINED PROTEIN-KINASE-C-INDEPENDENT HERBIMYCIN-A-SENSITIVE ACTIVATION OF EXTRACELLULAR SIGNAL-RELATED KINASE-1 2 IN THE RABBIT AORTA IN ORGAN-CULTURE/

The 42- and 44-kD mitogen-activated protein kinases, also referred to as extracellular signal-related kinase (ERK) 2 and 1, respectively, ma y be transiently activated by stretching vascular smooth muscle cells (VSMCs). Using an organ culture model of rabbit aorta, we studied shor t- and long-term ERK1/2 activation by intraluminal pressure (150 mm Hg ). Activation of ERK1/2 was biphasic: it reached a maximum (217.5+/-8. 4% of control) 5 minutes after pressurizing and decreased to 120.7+/-5 .1% of control after 2 hours. Furthermore, after 24 hours of pressuriz ing, ERK1/2 activity was as high (241.8+/-14.7% of control) as in the acute phase. Long-term pressure-induced ERK1/2 activation correlated w ith stimulation of tyrosine phosphorylation of proteins in the 125- to 140-kD range. Neither protein kinase C inhibitors (1 mu mol/L stauros porine or 50 mu mol/L bisindolylmaleimide-I) nor tyrosine kinase inhib itors (50 mu mol/L tyrphostin A48 or 50 mu mol/L genistein) affected p ressure-induced ERK1/2 activation. However, the Src-family tyrosine ki nase inhibitor herbimycin A (500 nmol/L) did reduce both 5-minute (by 92+/-8%) and 24-hour (by 63+/-7%) pressure-induced ERK1/2 activation. Thus, our results demonstrate a sustained activation of ERK1/2 and tyr osine kinases by intraluminal pressure in the arterial wall. Pressure- induced ERK1/2 activation is PKC independent and Src-family tyrosine k inase dependent and possibly includes activation of extracellular matr ix-associated tyrosine kinases.