Lack of nitric oxide synthase depresses ion transporting enzyme function in cardiac muscle.
Nitric oxide (NO*) is produced endogenously from NOS isoforms bound to sarcolemmal (SL) and sarcoplasmic reticulum (SR) membranes. To investigate whether locally generated NO* directly affects the activity of enzymes mediating ion active transport, we studied whether knockout of selected NOS isoforms would affect the functions of cardiac SL (Na+ + K+)-ATPase and SR Ca2+-ATPase. Cardiac SL and SR vesicles containing either SL (Na+ + K+)-ATPase or SR Ca2+-ATPase were isolated from mice lacking either nNOS or eNOS, or both, and tested for enzyme activities. Western blot analysis revealed that absence of single or double NOS isoforms did not interrupt the protein expression of SL (Na+ + K+)-ATPase and SR Ca2+-ATPase in cardiac muscle cells. However, lack of NOS isoforms in cardiac muscle significantly altered both (Na+ + K+)-ATPase activity and SR Ca2+-ATPase function. Our experimental results suggest that disrupted endogenous NO* production may change local redox conditions and lead to an unbalanced free radical homeostasis in cardiac muscle cells which, in turn, may affect key enzyme activities and membrane ion active transport systems in the heart.
Zhou
Lan
L
Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, USA.
Burnett
Arthur L
AL
Huang
Paul L
PL
Becker
Lewis C
LC
Kuppusamy
Periannan
P
Kass
David A
DA
Kevin Donahue
J
J
Proud
David
D
Sham
James S K
JS
Dawson
Ted M
TM
Xu
Kai Y
KY
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D007425:Intracellular Membranes / Q000201:enzymology; D017136:Ion Transport; D051379:Mice; D018345:Mice, Knockout; D009206:Myocardium / Q000201:enzymology* / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D012508:Sarcolemma / Q000201:enzymology; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496321:Nos1 protein, mouse; C496322:Nos1 protein, rat; C496315:Nos3 protein, mouse; C496316:Nos3 protein, rat; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium