β-adrenoceptor-mediated regulation of matrix metalloproteinase-9 in fibroblasts

Abstract

Adrenoceptor signalling in fibroblasts: Intracellular cAMP levels were measured by a direct cAMP enzyme immunoassay. Isoprenaline (ISO, 1 μM) increased intracellular cAMP concentration by 1.3 and 4.8 fold, P<0.05, after 10 min in the NIH3T3 fibroblasts and human cardiac ventricular fibroblasts (HCVF) respectively. These effects were abolished by pre-treatment with propranolol (PROP, 10 μM; P<0.05). Nuclear translocation of phospho-CREB was increased by isoprenaline (0.1 μM) and phenylephrine (10 μM) increased in NIH3T3 fibroblasts (P<0.05). Western blot analysis indicated that isoprenaline (1 μM) and phenylephrine (10 μM) caused a biphasic increase in p38 MAPK and a sustained increase in ERK1/2 MAPK activation over a 30 min period in NIH3T3 fibroblasts. However, in HCVF cells, isoprenaline (1 μM) decreased ERKl/2 MAPK phosphorylation by 70% after 30 min, an effect abolished by propranolol (10 μM; ISO vs. ISO/PROP: 0.30±0.06 vs. 1.05±0.10 AU; P<0.05).