Buthionine sulfoximine treatment impairs rat diaphragm function.
Activation of the glutathione (GSH) redox cycle with production of glutathione disulfide (GSSG) has been shown to occur in the diaphragm during inspiratory resistive loading (RB). Buthionine sulfoximine (BSO) lowers tissue GSH by irreversibly inhibiting the rate-limiting synthesis enzyme gamma-glutamylcysteine synthetase. We investigated the effects of BSO on rat diaphragm function, both at rest and after a period of RB. Rats in the RB groups underwent inspiratory RB until they were unable to sustain 70% of their maximal airway pressure. A portion of the diaphragm was analyzed for GSH and GSSG levels, and measurements of in vitro contractile properties included contraction times, maximal tetanic tension (Po), maximal twitch tension (Pt), and force frequency curves. BSO treatment produced a profound depletion of diaphragmatic GSH. Neither BSO nor RB alone significantly altered diaphragm contractile properties at this load of RB. But, in BSO-RB rats, there was a significant decrease in Pt, Po, and tetanic tension at all frequencies of stimulation compared with those in other groups. These data reveal that animals treated with BSO followed by inspiratory resistive loading exhibit marked diaphragm impairment, suggesting that GSH may play an important role in protecting the diaphragm from the stress induced by this resistive breathing protocol.
Morales
C F
CF
Division of Pulmonary Diseases/Critical Care Medicine, University of Texas Health Science Center at San Antonio 78284-7885.
Anzueto
A
A
Andrade
F
F
Brassard
J
J
Levine
S M
SM
Maxwell
L C
LC
Lawrence
R A
RA
Jenkinson
S G
SG
D000704:Analysis of Variance; D000818:Animals; D019328:Buthionine Sulfoximine; D003964:Diaphragm / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D005721:Glutamate-Cysteine Ligase / Q000037:antagonists & inhibitors*; D005978:Glutathione / Q000031:analogs & derivatives / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D019803:Glutathione Disulfide; D008297:Male; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012129:Respiratory Function Tests / Q000706:statistics & numerical data
D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D019803:Glutathione Disulfide