K. Mikawa et al., ONO-1714, a new inducible nitric oxide synthase inhibitor, attenuates diaphragmatic dysfunction associated with cerulein-induced pancreatitis in rats, CRIT CARE M, 29(6), 2001, pp. 1215-1221
Objectives. Acute experimental pancreatitis (induced by cerulein) recently
has been reported to cause marked diaphragmatic dysfunction, which may cont
ribute to respiratory distress in this setting. In cerulein-induced acute p
ancreatitis, expression of inducible nitric oxide synthase is induced to pr
oduce a large amount of nitric oxide. Nitric oxide excessively produced has
been implicated in diaphragmatic dysfunction induced by a variety of etiol
ogies. The aims of the current study were, first, to examine whether nitric
oxide overproduced through inducible nitric oxide synthase is involved in
cerulein-induced impairment of diaphragmatic function, and second, if demon
strated, to assess effects of ONO-1714, an inducible nitric oxide synthase
inhibitor, on diaphragmatic dysfunction associated with cerulein-induced ac
ute pancreatitis.
Design: Prospective, randomized animal study.
Setting: University research laboratory.
Subjects: Ninety-one male Sprague-Dawley rats, weighing 200-250 g.
Interventions: Rats were randomly divided into seven groups (n = 8 each): C
ONT-SAL, GAER-SAL, CONT-ONO, GAER-DEX, CAER-AMI, GAER-ONOhigh, and GAER-ONO
low. Groups labeled CAER received two consecutive intraperitoneal doses (50
mug/kg) of cerulein, whereas groups labeled CONT received two consecutive
intraperitoneal injections of saline. Groups labeled SAL received intraperi
toneal saline before cerulein or saline. The group labeled DEX received 2 m
g/kg intraperitoneal dexamethasone, and the group labeled AMI received 100
mg/kg intraperitoneal aminoguanidine. The groups labeled ONO, ONOhigh, and
ONOlow received ONO-1714 at 0.1 mg/kg, 0.1 mg/kg, and 0.03 mg/kg, respectiv
ely, before cerulein or saline.
Measurements and Main Results: Diaphragmatic contractility and fatigability
were assessed in vitro by using muscle strips excised from the costal diap
hragms 6 hrs after the first dose of cerulein or saline. Expression of indu
cible nitric oxide synthase protein in the diaphragm was assessed by immuno
histochemistry by using anti-inducible nitric oxide synthase antibody. Plas
ma concentrations of nitrite plus nitrate and diaphragmatic concentrations
of malondialdehyde were measured. With another set of rats (n = 5 each grou
p), diaphragmatic inducible nitric oxide synthase activity was determined.
Twitch and tetanic tensions and tensions generated during fatigue trial wer
e lower in group CAER-SAL than in group CONT-SAL. Cerulein increased diaphr
agmatic malondialdehyde and plasma nitrite plus nitrate concentrations. Pos
itive immunostaining for inducible nitric oxide synthase protein was found
in group CAER-SAL. Dexamethasone and aminoguanidine attenuated the diaphrag
matic mechanical damages. A high dose of ONO-1714 attenuated cerulein-induc
ed impairment of diaphragmatic contractility and endurance capacity, althou
gh a low dose of the drug failed to do so.
Conclusions: Cerulein-induced diaphragmatic dysfunction was attributable, i
n part, to nitric oxide overproduced via inducible nitric oxide synthase. P
retreatment with ONO-1714 at a dose of 0.1 mg/kg attenuated diaphragmatic d
ysfunction associated with cerulein-induced pancreatitis in rats assessed b
y contractile profiles and endurance capacity. This beneficial effect of ON
O-1714 may be attributable, in part, to inhibition of diaphragmatic lipid p
eroxidation induced by nitric oxide-derived free radicals.