3-I-1. Effects of OLM on body weight, left ventricular weight and aortic pressure
The CRF rats yielded a decrease in BW and a significant increase in LVW and
LVW/BW ratio (Table 1). LVW and LVW/BW ratio were reduced with significance
after OLM treatment for 8 weeks. In comparing with the age-matched normal controls,
aortic systolic pressure, aortic diastolic pressure, and mean aortic pressure were all
increased in the CRF rats. After exposure to OLM, the CRF rats exhibited significant
decreases in all of the arterial blood pressure profiles.
Table 1. Effects of OLM on body weight, left ventricular weight and aortic pressure
between normal rats and subtotal nephrectomy-induced CRF rats.
Data are expressed as means ± SEs.
Abbreviations: BW, body weight; Ps, aortic systolic pressure; Pd, aortic diastolic
pressure; Pm, mean aortic pressure; LVW, left ventricular weight.
* : P < 0.05, CRF vs. NC; † :P < 0.05, CRF+OLM vs. CRF
Measurement NC
(n = 13)
CRF
(n = 14)
CRF+OLM
(n = 14)
BW (g) 480 ± 11.9 412.1 ± 16.6* 443.6 ± 10.5
LVW (g) 0.98 ± 0.03 1.2 ± 0.04* 0.94 ± 0.05†
LVW/BW (‰) 2.04 ± 0.05 2.9 ± 0.11* 2.11 ± 0.08†
Ps (mm Hg) 117.2 ± 2.2 178.5 ± 8.6* 135.7 ± 6.2†
Pd (mm Hg) 94.2 ± 2.3 126.9 ± 5.2* 101.8 ± 6.1†
Pm (mm Hg) 106.7 ± 2.3 152.1 ± 6.4* 119.2 ± 6.1†
3-I-2. Changes in renal function after OLM treatments
There were significant changes in renal function as shown by the differences in
clearances of BUN and SCr between normal rats and CRF rats (Table 2). At week 8
after the induction of CRF, the BUN was 3.3-fold and SCr 2.6-fold higher in CRF rats
than the controls (P < 0.05), indicating an impaired renal function. We observed
significant increases in the clearances of both BUN and SCr in the CRF rats following
OLM administration, of which BUN decreased by 28.7% (P < 0.05) and SCr 38.8% (P
< 0.05) when compared to those without treatment.
Table 2. Changes in renal function of 5/6 subtotal nephrectomy induced CRF rats with
or without OLM treatment for 8 weeks.
Data are expressed as means ± SEs.
Abbreviations: BUN, blood urea nitrogen; SCr, serum creatinine; NC, normal controls;
CRF, chronic renal failure; and OLM, olmesartan.
* : P < 0.05, CRF vs. NC; † :P < 0.05, CRF+OLM vs. CRF
3-I-3. Effects of OLM on static parameters
Figure 2 shows the effects of CRF and OLM on the static hemodynamics,
including basal heart rate (HR), cardiac output (CO), stroke volume (SV), and total
peripheral resistance (Rp). In comparison with normal controls, CRF rats showed
significantly affected hemodynamics characterized by decreased HR (396.26±10.76 vs.
364.30±10.02 beats/min, P <0.05) and CO (2.30±0.09 vs. 2.07±0.09 ml/sec, P <0.05)
(Figure 2, A, B), and conversely, a marked increase in Rp (P < 0.05) (Figure 2, D). The
decrease in CO coupled with the increase in mean aortic pressure in CRF rats (Table 1)
caused a marked rise in Rp. After 8 weeks of OLM treatment, CRF rats were normalized
as evidenced by increased CO (2.07±0.09 vs. 2.28±0.09 ml/sec, P <0.05) and decreased
Rp (74.56±3.43 vs. 53.52±3.77, mmHg sec/mL, P <0.05) (Figure 2, B, D).
(A) (B)
HR, basal heart rate (beats min-1)
0
Rp, total peripheral resistance (mmHg s ml-1)
0
Figure 2. Effects of OLM treatment on induced CRF rats and comparisons among
different groups (n=14 in each group). HR, heart rate (A); CO, cardiac output (B); SV,
stroke volume (C); Rp, total peripheral resistance (D); NC, normal controls; CRF,
chronic renal failure; OLM, olmesartan.
3-I-4. Effects of OLM on pulsatile parameters
Figure 3 shows the effects of CRF and OLM on the pulsatile nature of blood flows
in arteries in terms of aortic characteristic impedance (Zc), aortic compliance (Cm), wave
transit time (τ), and wave reflection factor (Rf). The aortic characteristic impedance
(Bethesda 2003) and wave reflection factor were significantly increased in CRF rats
compared to controls (Zc, 2.23±0.21 vs. 1.19±0.05; Rf, 0.76±0.03 vs. 0.54±0.03 mmHg
sec/ mL, P < 0.05) (Figure 3, A, C). These changes were accompanied by the decreases
of aortic compliance (13.50±0.60 vs. 5.03±0.46, P < 0.05, Figure 3C) and wave transit
time (27.62±1.02 vs. 16.26±0.59 ms, P < 0.05, Figure 3, D). Treatment with OLM
showed significant effects on retarding the CRF-induced mechanical alterations in the
Windkessel vessels (Table 1), as manifested by the 39% reduction in aortic
characteristic impedance (Zc, 2.23±0.21 vs. 1.36±0.08, P < 0.05) and the 75.3% increase
in aortic compliance (Cm,5.03±0.46 vs. 8.82±0.92, P <0.05). Early return with the
augmented magnitude of the reflected wave from the peripheral circulation in CRF rats
was impeded following OLM treatment, as demonstrated by the increase of 50.3% in
wave transit time (τ, 16.26±0.59 vs. 24.44±1.76, P < 0.05).
(A) (B)
ZC, aortic characteristic impedance (mmHg s ml -1)
0.0
Cm aortic compliance at Pm (ml mmHg-1)
0.0
Figure 3. Effects of OLM treatment on induced CRF rats and comparisons among
different groups (n=14 in each group). Zc, aortic characteristic impedance (A); Cm,
systemic arterial compliance (B); Rf , wave reflection factor (C); τ, wave transit time (D);
NC, normal controls; CRF, chronic renal failure; OLM, olmesartan.
3-I-5. Effects of OLM on AGE accumulation
The immunointensity indicating AGE accumulation was higher in the media of
aortic wall of CRF rats (Figure 4), which was significantly reduced following OLM
treatment for 8 weeks.
Figure 5 shows the Western blot profiles of aortic collagen. The amount of AGEs
was 142% increased in collagen samples from CRF rats compared with control samples,
displaying a molecular weight fragments between 26 and 34 KDa. After treatment with
OLM for 8 weeks, AGEs decreased by 32% in glycation-derived modification of aortic
collagen (P < 0.05).
(A) (B)
(C)
Figure 4. Immunohistochemical staining for advanced glycation end products (AGEs)
in the aortas at 8 weeks after SNx. NC, normal controls; CRF, chronic renal failure;
NC CRF
CRF+OLM
AGEs level
0.0 1.0 2.0
3.0 P < 0.05 P < 0.05
NC CRF CRF+OLM Aorta
Figure 5. Representative Western blot and the corresponding level of advanced
glycation end products (AGEs) in the aortas of rats (n=5) analyzed by densitometry.
Lane 1: NC; 2: NC+OLM; lane 3: CRF; lane 4: CRF+OLM. All data were normalized
to the NC. NC, normal controls; CRF, chronic renal failure; OLM, olmesartan.
AGEs
3-I-6. Effects of OLM on MDA
Figure 6 shows the levels of malondialdehyde (MDA) equivalents in the aorta and
in serum. MDA is a biomarker of lipid-related oxidative stress, which indicates the
degree of lipid peroxidation. The levels of MDA equivalents of the aorta and serum in
CRF rats were markedly increased than that of controls, ranging from 1.50 ± 0.05 to
2.02 ± 0.04 nmol mg-1 protein (P < 0.05) in aorta and from 12.67 ± 1.13 to 17.01 ± 0.78
mM (P < 0.05) in serum. OLM treatment prevented CRF-induced oxidative stress in
both aorta and serum, as evidenced by the reductions of levels of MDA equivalents by
14.3% and 25.1%, respectively.
(A) (B)
Figure 6. The levels of malondialdehyde (MDA) equivalents in the aorta (A) and serum
(B) measured by TBARS assay. Increased level of MDA equivalents was observed in
rats with CFR, and decreased in CRF rats (n=12) following OLM treatment. NC,
normal controls; CRF, chronic renal failure; OLM, olmesartan.