XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Lectures
THE CROSS-TALK OF NITRIC OXIDE AND NUCLEar faCTOr kaPPa B
IN EXPERIMENTAL HYPErTENSION
Olga Pecháňová, Andrej Barta, Stanislava Vranková,
Jana Parohová and Mária Kovácsová
Institute of Normal and Pathological Physiology and Centre of Excellence
for Cardiovascular Research, Slovak Academy of Sciences, Bratislava, Slovak Republic
Recently we have demonstrated involvement of NF-κB in the upregulation of endothelial
nitric oxide synthase (eNOS) in hypertension induced by N G -nitro-L-arginine methyl
ester (L-NAME). Thus, the goal of our study was to analyze an effect of NF-κB inhibitor,
lactacystin, in L-NAME-induced hypertension. Adult 12-week-old male Wistar rats were
subjected to treatment with L-NAME (40 mg/kg/day) for seven weeks (n=14). Half of
the rats received lactacystin together with L-NAME for last three weeks. Next 16-weekold
male Wistar rats received lactacystin only for 3 weeks (n=7). Blood pressure was
measured by tail-cuff plethysmography every week. Total NOS activity was determined
by measuring the formation of L-[ 3 H] citrulline from L-[ 3 H] arginine. Endothelial NOS
and NF-κB (p65) protein expressions were determined immunohistochemically and by
Western blot analysis. Membrane oxidative damage was analyzed by conjugated diene
(CD) level determination. Lactacystin treatment did not affect the blood pressure (103±6
mmHg), while 7-week-L-NAME treatment increased blood pressure (141±3 mmHg) by 38%
comparing the age-matched untreated animals (104±5 mmHg). Addition of lactacystin to
the L-NAME increased blood pressure significantly (159±4 mmHg) by 54% comparing the
untreated control group and by 12% comparing the L-NAME group. L-NAME treatment
led to increased NF-κB expression followed by elevation of both eNOS protein expression
and total NOS activity in the aorta, heart and kidney. Addition of lactacystin blocked,
however, elevated eNOS protein expression in all tissues investigated. CD concentration
was increased by lactacystin treatment.
We hypothesized that NF-κB is responsible for upregulation of eNOS protein expression
which may represent one of the counterregulatory mechanisms activated to compensate
decreased NO production and increased blood pressure after long-term L-NAME treatment.
Acknowledgements: This study was supported by the grants VEGA 2/0178/09 and
APVV-0538-07.
XXII. Biochemistry Congress, Martin
87