title: Inhibition of Na+/Ca2+ exchanger by peroxynitrite in microsomes of pulmonary smooth muscle: role of matrix metalloproteinase-2.
abstract: Treatment of bovine pulmonary artery smooth muscle microsomes with peroxynitrite (ONOO-) (100 microM) markedly stimulated matrix metalloproteinase-2 (MMP-2) activity and also enhanced Ca2+ATPase activity and ATP-dependent Ca2+ uptake. Pretreatment of the microsomes with vitamin E (1 mM) and TIMP-2 (50 microg/ml) preserved the increase in MMP-2 activity, Ca2+ATPase activity and also ATP-dependent Ca2+ uptake in the microsomes. In contrast, Na(+)-dependent Ca2+ uptake in the microsomes was inhibited by ONOO- and this was found to be reversed by vitamin E (1 mM) and TIMP-2 (50 microg/ml). However, changes caused by ONOO- in MMP-2 activity, ATP-dependent Ca2+ uptake and Na(+)-dependent Ca2+ uptake were not reversed upon pretreatment of the microsomes with a low concentration of 5 microg/ml of TIMP-2 which, on the contrary, reversed MMP-2 (1 microg/ml)-mediated alteration on these parameters. The inhibition of Na(+)-dependent Ca2+ uptake by ONOO- and MMP-2 overpowered the stimulation of ATP-dependent Ca2+ uptake in the microsomes. Treatment with ONOO- abolished the inhibitory effect of TIMP-2 (5 microg/ml) on MMP-2 (1 microg/ml) causing 14C-gelatin degradation. Overall, the present study suggests that ONOO- inactivated TIMP-2, the ambient inhibitor of MMP-2, leading to activation of the ambient proteinase, MMP-2, and subsequently stimulated Ca2+ATPase activity and ATP-dependent Ca2+ uptake, but inhibited Na(+)-dependent Ca2+ uptake, resulting in a marked decrease in Ca2+ uptake in microsomes of bovine pulmonary artery smooth muscle.
authors.affiliation: Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal, India. saj_chakra@rediffmail.com
authors.forename: Sajal
authors.initials: S
authors.lastname: Chakraborti
authors.forename: Amritlal
authors.initials: A
authors.lastname: Mandal
authors.forename: Sudip
authors.initials: S
authors.lastname: Das
authors.forename: Tapati
authors.initials: T
authors.lastname: Chakraborti
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002417:Cattle; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D008861:Microsomes / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D011651:Pulmonary Artery / Q000033:anatomy & histology; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014810:Vitamin E / Q000378:metabolism
chemical_list: D000975:Antioxidants; D019831:Sodium-Calcium Exchanger; D019716:Tissue Inhibitor of Metalloproteinase-2; D014810:Vitamin E; D030421:Peroxynitrous Acid; D000255:Adenosine Triphosphate; D012964:Sodium; D020778:Matrix Metalloproteinase 2; D000252:Calcium-Transporting ATPases; D002118:Calcium