Involvement of a protease in tert-butylhydroperoxide-mediated activation of Ca2+ ATPase in microsomes of pulmonary smooth muscle.
Microsomes isolated from bovine pulmonary artery smooth muscle tissue treated with the oxidant t-buOOH stimulated Ca2+ ATPase activity dose-dependently as also protease activity when tested with a synthetic substrate N-benzoyl-DL-arginine p-nitroanilide. At 300 microM, t-buOOH optimally stimulated these activities. Treatment of the microsomes with t-buOOH stimulated ATP dependent Ca2+ uptake while Na+ dependent Ca2+ uptake was inhibited by t-buOOH. Pretreatment of the microsomes with vitamin E (1 mM) and aprotinin (1 mg/ml) prevented t-buOOH caused stimulation of protease activity and Ca2+ ATPase activity, and also stimulation of ATP dependent Ca2+ uptake while t-buOOH caused inhibition of Na+ dependent Ca2+ uptake was reversed by vitamin E and aprotinin. Treatment of the microsomes with trypsin (1 microgram/ml) stimulated Ca2+ ATPase and ATP dependent Ca2+ uptake while Na+ dependent Ca2+ uptake was inhibited. Pretreatment of the microsomes with aprotinin prevented trypsin caused stimulation of Ca2+ ATPase and ATP dependent Ca2+ uptake, while trypsin caused inhibition of Na+ dependent Ca2+ uptake was reversed by aprotinin.
Ghosh
S K
SK
Department of Biochemistry and Biophysics, University of Kalyani, West Bengal, India.
Chakraborti
T
T
Selvamurthy
W
W
Roychoudhury
S
S
Chakraborti
S
S
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002417:Cattle; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D008168:Lung / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism; D010545:Peroxides / Q000494:pharmacology; D020122:tert-Butylhydroperoxide
D010545:Peroxides; D020122:tert-Butylhydroperoxide; D010450:Endopeptidases; D000252:Calcium-Transporting ATPases; D002118:Calcium