title: Changes in myocardial contractile protein ATPases in chronically adrenalectomized rats with and without glucocorticoid replacement.
abstract: Studies were conducted to examine the effects of chronic adrenalectomy (Adx) and adrenalectomy plus glucocorticoid replacement therapy on rat cardiac contractile protein ATPase activities. The Ca2+-dependent Mg-ATPase activity of myofibrils isolated from rat ventricles 3 weeks postadrenalectomy (Adx) was significantly decreased at all pCa2+ concentrations (P less than 0.01), compared to sham-operated (SO) rats. Similarly, Ca2+-, K+-EDTA, and actin-activated myosin ATPase activities of Adx rat hearts were markedly decreased below that of SO rats (P less than 0.01). Dexamethasone administration to Adx rats prevented the decrease of Ca2+- and K+-ATPase activities of myosin, but not of myofibrillar Ca2+-dependent Mg-ATPase or actin-activated myosin Mg-ATPase activities. These studies suggest that glucocorticoid insufficiency induced by adrenalectomy results in altered myocardial contractile protein ATPase activity which may underlie impaired cardiac performance.
authors.affiliation: Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City.
authors.forename: M
authors.initials: M
authors.lastname: Bhaskar
authors.forename: R D
authors.initials: RD
authors.lastname: Stith
authors.forename: D J
authors.initials: DJ
authors.lastname: Brackett
authors.forename: M F
authors.initials: MF
authors.lastname: Wilson
authors.forename: M R
authors.initials: MR
authors.lastname: Lerner
authors.forename: Y S
authors.initials: YS
authors.lastname: Reddy
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000315:Adrenalectomy; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D003345:Corticosterone / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D009210:Myofibrils / Q000201:enzymology; D009218:Myosins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D005938:Glucocorticoids; D003907:Dexamethasone; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; C026049:EDTA-ATPase; D009218:Myosins; D000252:Calcium-Transporting ATPases; D003345:Corticosterone