Collagen Fraction Research Articles

Is diminished pubocervical fascia collagen content a risk factor for failure of surgical management of genuine stress urinary incontinence in women?

Objective: The assessment of relationship between pubocervical collagen content and clinical results of surgical treatment of genuine stress urinary incontinence (GSUI) in women. Methods: Twenty-four women treated for genuine stress urinary incontinence were included into the study. All women underwent the same surgical procedure. The samples of pubocervical fascia were taken at the time of surgery. The contents of acid soluble, pepsin soluble, insoluble fraction of collagen, total collagen and collagen crosslinks were measured. The study of pubocervical fascia collagen metabolism included also estimation of collagenase activity. At follow-up done 5 years following surgery, 20 patients reported symptoms of GSUI (study group). Four women were still without symptoms of urine leakage (control group). Results: The biochemical parameters of pubocervical fascia did not show, statistically significant differences between compared groups. Conclusion: The pubocervical fascia collagen metabolism does not have impact on the results of anti-incontinence surgery.

Molecular species of collagen from wing muscle of skate ( Raja kenojei )

Soluble collagen was prepared from skate ( Raja kenojei ) wing muscle by limited pepsin digestion. It was fractionated into two fractions, major and minor, by differential ammonium sulfate precipitation. Two collagen types were purified from the major and minor collagen fractions by phosphocellulose column chromatography and were identified as Type I and V collagens, respectively, by SDS-PAGE, peptide mapping, and amino acid analysis.

Ontogenetic changes in fibrous connective tissue organization in the oval squid, Sepioteuthis lessoniana Lesson, 1830.

Ontogenetic changes in the organization and volume fraction of collagenous connective tissues were examined in the mantle of Sepioteuthis lessoniana, the oval squid. Outer tunic fiber angle (the angle of a tunic collagen fiber relative to the long axis of the squid) decreased from 33.5 degrees in newly hatched animals to 17.7 degrees in the largest animals studied. The arrangement of intramuscular collagen fiber systems 1 (IM-1) and 2 (IM-2) also changed significantly during ontogeny. Because of the oblique trajectory of the IM-1 collagen fibers, two fiber angles were needed to describe their organization: (1) IM-1(SAG), the angle of an IM-1 collagen fiber relative to the squid's long axis when viewed from a sagittal plane and (2) IM-1(TAN), the angle of an IM-1 collagen fiber relative to the squid's long axis when viewed from a plane tangential to the outer curvature of the mantle. The sagittal component (IM-1(SAG)) of the IM-1 collagen fiber angle was lowest in hatchling squid (32.7 degrees ) and increased exponentially during growth to 43 degrees in squid with a dorsal mantle length (DML) of 15 mm. In squid larger than 15 mm DML, IM-1(SAG) fiber angle did not change. The tangential component (IM-1(TAN)) of IM-1 collagen fiber angle was highest in hatchling squid (39 degrees ) and decreased to 32 degrees in the largest squid examined. IM-2 collagen fiber angle (the angle of an IM-2 collagen fiber relative to the outer surface of the mantle) was lowest in hatchling squid (34.6 degrees ) and increased exponentially to about 50 degrees in 15-mm DML animals. In squid larger than 15 mm DML, IM-2 fiber angle increased slightly with size. The volume fraction of collagen in IM-1 and IM-2 increased 68 and 36 times, respectively, during growth. The ontogenetic changes in the organization of collagen fibers in the outer tunic, IM-1, and IM-2 may lead to ontogenetic differences in the kinematics of mantle movement and in elastic energy storage during jet locomotion.

Long-term effect of N-acetyl-seryl-aspartyl-lysyl-proline on left ventricular collagen deposition in rats with 2-kidney, 1-clip hypertension.

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a natural inhibitor of pluripotent hematopoietic stem cell proliferation. Ac-SDKP plasma concentration is increased 5-fold after angiotensin-converting enzyme inhibition. Here we studied the effect of Ac-SDKP on monocyte/macrophage infiltration, fibroblast proliferation, and collagen deposition in the rat heart in renovascular hypertension. We investigated whether long-term Ac-SDKP administration would prevent left ventricular (LV) hypertrophy and interstitial collagen deposition in rats with 2-kidney, 1-clip (2K-1C) hypertension. Ac-SDKP (400 microgram. kg(-1). d(-1)) did not affect development of hypertension. Mean blood pressure was similar in rats with 2K-1C hypertension whether they were given vehicle or Ac-SDKP and was higher than in controls. Both LV weight and cardiomyocyte size were significantly increased in rats with 2K-1C hypertension compared with controls and were unaffected by Ac-SDKP. Proliferating cell nuclear antigen- and monocyte/macrophage-positive cells were increased in the LV of 2K-1C hypertensive rats; this increase was significantly blunted by Ac-SDKP (P<0.001). LV interstitial collagen fraction was also increased in 2K-1C hypertensive rats given vehicle (10.1+/-0.8%) compared with sham (5.3+/-0.1%, P<0.0001), and this increase was prevented by Ac-SDKP (5.4+/-0.4%, P<0.001). Ac-SDKP inhibited monocyte/macrophage infiltration, cell proliferation, and collagen deposition in the LV of hypertensive rats without affecting blood pressure or cardiac hypertrophy, suggesting that it may be partly responsible for the cardioprotective effect of angiotensin-converting enzyme inhibitors.

Relation of thallium uptake to morphologic features of chronic ischemic heart disease: evidence for myocardial remodeling in noninfarcted myocardium

OBJECTIVESThe aim of this study was to investigate the disparity between the extent of myocardial injury as assessed by thallium and the severity of left ventricular (LV) dysfunction in chronic ischemic heart disease.BACKGROUNDAlthough it is believed that thallium differentiates between viable and nonviable myocardium, in some patients with chronic ischemic heart disease, viable regions by thallium may fail to improve function after revascularization.METHODSThirteen transplant candidates with chronic ischemic heart disease (LV ejection fraction = 14 ± 6% at rest) were studied prospectively with stress-redistribution-reinjection thallium single-photon emission computed tomography. We examined pretransplantation quantitative thallium uptake and post-transplantation extent and the histological distribution of collagen replacement in infarcted and noninfarcted myocardium and in 13 age-matched control hearts.RESULTSThe volume fraction of collagen varied inversely with wall thickness (r = −0.70, p < 0.001) and was higher in irreversible (30.9 ± 15.8%) compared with reversible (20.2 ± 12.6%, p < 0.001) or normal thallium segments (15.0 ± 8.7%, p < 0.001). The irreversible thallium segments had lower wall thickness and more severe coronary artery narrowing (9.7 ± 2.8 mm and 95 ± 8%) compared with reversible (11.7 ± 2.7 mm and 87 ± 13%, p < 0.001) and normal thallium segments (12.8 ± 2.6 mm and 80 ± 14%, p < 0.001). Mean volume fraction of collagen was significantly lower in noninfarcted than it was in infarcted segments (13 ± 6% vs. 36 ± 13%, p < 0.001) but exceeded that in the control hearts (4 ± 2%, p < 0.001). Noninfarcted segments had predominantly interstitial fibrosis with either microscopic or patchy areas of replacement fibrosis.CONCLUSIONSIn chronic ischemic heart disease with severe LV dysfunction, patterns of normal, reversible and irreversible thallium uptake correlated with the magnitude of collagen replacement, segmental wall thickness and severity of coronary artery narrowing. The finding of scattered areas of replacement fibrosis in noninfarcted myocardium may explain the observed disparity between LV contractile dysfunction and the extent of myocardial injury assessed by thallium.

Diminished cardioprotective response to inhibition of angiotensin-converting enzyme and angiotensin II type 1 receptor in B(2) kinin receptor gene knockout mice.

Using B(2) kinin receptor gene knockout mice (B(2)(-/-)), we tested the hypothesis that (l) lack of B(2) receptors may affect blood pressure and cardiac function and aggravate cardiac remodeling after myocardial infarction (MI), and (2) kinins partially mediate the cardiac beneficial effect of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II type 1 receptor antagonists (AT(1)-ant), whereas lack of B(2) receptors may diminish this cardioprotective effect. Chronic heart failure (HF) was induced by MI, which was caused by coronary artery ligation in both B(2)(-/-) and 129/SvEvTac mice (wild-type control, B(2)(+/+)). An ACEi (ramipril, 2.5 mg/kg/d) or AT(1)-ant (L-158809, 3 mg/kg/d) was given 1 week after MI and was continued for 12 weeks. Left ventricular (LV) ejection fraction, cardiac output (CO), diastolic LV dimension (LVDd), and LV mass were evaluated by echocardiography. Myocyte cross-sectional area and interstitial collagen fraction were studied histopathologically. We found that basal blood pressure and cardiac function were similar in B(2)(+/+) and B(2)(-/-) mice. After MI, development of HF and remodeling were also similar between the 2 strains. The ACEi improved cardiac function and remodeling in both strains; however, its effects were attenuated in B(2)(-/-) mice (respective values for B(2)(+/+) versus B(2)(-/-) mice: overall increase in ejection fraction, 64+/-10% versus 21+/-5% [P<0.01]; increase in CO, 69+/-17% versus 23+/-9% [P<0.01]; overall decrease in LVDd, -24+/-3% versus -7+/-4% [P<0.01]; and decrease in LV mass, -38+/-3% versus -6+/-6% [P<0.01]). AT(1)-ant had a beneficial cardiac effect similar to that produced by ACEi, and this effect was also diminished in B(2)(-/-) mice (respective values for B(2)(+/+) versus B(2)(-/-) mice: overall increase in ejection fraction, 46+/-10% versus 25+/-9% [P<0.01]; increase in CO, 44+/-14% versus 15+/-5% [P<0.01]; overall decrease in LVDd, -14+/-4% versus -6+/-3% [P<0.01]; and decrease in LV mass, -33+/-4 versus -16+/-7% [P<0.01]). The effect of ACEi or AT(1)-ant on myocyte cross-sectional area was similar between strains; however, their effect on the interstitial collagen fraction was diminished in B(2)(-/-) mice. We concluded that (1) lack of B(2) kinin receptors does not affect cardiac phenotype or function, either under normal physiological conditions or during the development of HF; and (2) kinins acting via the B(2) receptor play an important role in the cardioprotective effect of ACEi and AT(1)-ant.

Effect of matrix metalloproteinase inhibition on colonic anastomotic healing in rats

Wound strength depends on the balance between collagen synthesis and degradation; however, the role of collagen breakdown in wound healing is still not well understood. We investigated the role of matrix metalloproteinases in wound healing by using BE16627B, a matrix metalloproteinase inhibitor. Identical surgical procedures consisting of a colonic anastomosis (single-layer, inverted) and implantation of an osmotic pump in the back were performed in male Sprague-Dawley rats weighing 270 to 290 grams. The animals were randomly assigned to receive either BE16627B (n = 10) dissolved in dimethylsulfoxide and diluted with ethylene glycol at a dosage of 2.4 mg/rat/day for 3 days or the vehicle solution alone (n = 11). The solutions were administered through the surgically implanted osmotic pumps. The animals were killed 4 days after surgery, and the colonic bursting pressure (mm Hg) and hydroxyproline concentration (μg/mg wet tissue, index of collagen) were measured. The administration of BE16627B enhanced colonic anastomotic healing, as measured by the increase in the colonic bursting pressure (160 ± 12 vs. 125 ± 7 mm Hg; P <0.05) and the increase in the soluble fraction of collagen (0.27 ± 0.01 vs. 0.21 ± 0.01 μg/mg wet tissue; P < 0.01) in the anastomosis. Histologic examination of the tissue revealed that the use of BE16627B resulted in the preservation of the multilayered colonic structure and increased the network of collagen between both ends of the colon in the thickening submucosal layer. These findings demonstrate that the inhibition of matrix metalloproteinase activity influences colonic anastomotic healing, indicating a potential mechanism for enhancing anastomotic healing.

Identification and Characterization of Molecular Species of Collagen in Fish Skin

ABSTRACT: Pepsin‐solubilized collagen (PSC) prepared from the skin of 3 fish species—common horse mackerel, yellow sea bream, and tiger puffer—were separated into 2 fractions, major and minor, by ammonium sulfate precipitation. These collagen fractions were further purified by phosphocellulose column chromatography. From the results of SDS‐PAGE, peptide mapping, and amino‐acid analysis, the purified major and minor collagens were identified to be type I and V collagens, respectively. These results suggest that type V collagen might be widely present in fish skin as a minor collagen.

Carboxymethyllysine in Dermal Tissues of Diabetic and Nondiabetic Patients with Chronic Renal Failure: Relevance to Glycoxidation Damage

Carboxymethyllysine (CML) is currently recognized as a major advanced glycation end product and a marker for glycoxidation. Plasma CML levels are increased in patients with chronic renal failure (CRF). However, significance and mechanism of CML accumulation in these patients are poorly understood. The objective of the present study was to analyze CML in soluble and collagen-binding fractions of the dermis to investigate CML deposition and formation and collagen damage related to CML accumulation in patients with CRF. Skin samples (among them autopsy samples) were obtained from 33 subjects: 8 nondiabetic CRF patients, 7 diabetic predialysis patients with CRF (CRF-DM), 7 hemodialysis patients, and 11 control subjects without either CRF or DM. The dermal samples were extracted sequentially by phosphate-buffered normal saline, pepsin, and collagenase. The extracts were referred to as the soluble fraction and the proteinase-extracted fraction (including pepsin-extracted and collagenase-extracted fractions). Our ELISA assay for CML in dermal collagen from predialysis patients with CRF (CRF and CRF-DM groups) demonstrated that the levels of CML in both the soluble fraction (containing soluble CML which was mainly determined by serum clearance) and the structural collagen-binding proteinase-extracted fraction (in which high CML levels could be a strong indication of in situ formation) were increased and could not be completely reduced after hemodialysis in CRF-DM and CRF groups. These results suggest that accumulation of CML may be due to both a low serum clearance and/or increased in situ CML formation in CRF. CML contents in the proteinase extracted fraction inversely correlated with the susceptibility of collagen to extraction by proteinases (n = 33, r = –0.59, p < 0.001). Our results provide the first biochemical evidence that CML level is increased in both the soluble and collagen-binding fractions and that increased CML level resulted in increased fractions of proteinase-resistant collagen in dermal extracts of patients with CRF.

Hyperoxia and Recovery from Hypoxia Alter Collagen in Peripheral Pulmonary Arteries Similarly

Chronic hypoxia causes pulmonary hypertension, the mechanism of which includes altered collagen metabolism in the pulmonary vascular wall. This chronic hypoxic pulmonary hypertension is gradually reversible upon reoxygenation. The return to air after the adjustment to chronic hypoxia resembles in some aspects a hyperoxic stimulus and we hypothesize that the changes of extracellular matrix proteins in peripheral pulmonary arteries may be similar. Therefore, we studied the exposure to moderate chronic hyperoxia (FiO2 = 0.35, 3 weeks) in rats and compared its effects on the rat pulmonary vasculature to the effects of recovery (3 weeks) from chronic hypoxia (FiO2 = 0.1, 3 weeks). Chronically hypoxic rats had pulmonary hypertension (Pap = 26±3 mm Hg, controls 16±1 mm Hg) and right ventricular hypertrophy. Pulmonary arterial blood pressure and right ventricle weight normalized after 3 weeks of recovery in air (Pap = 19±1 mm Hg). The rats exposed to moderate chronic hyperoxia also did not have pulmonary hypertension (Pap = 18±1 mm Hg, controls 17±1 mm Hg). Collagenous proteins isolated from the peripheral pulmonary arteries (100-300 mm) were studied using polyacrylamide gel electrophoresis. A dominant low molecular weight peptide (approx. 76 kD) was found in hypoxic rats. The proportion of this peptide decreases significantly in the course of recovery in air. In addition, another larger peptide doublet was found in rats recovering from chronic hypoxia. It was localized in polyacrylamide gels close to the zone of a2 chain of collagen type I. It was bound to anticollagen type I antibodies. An identically localized peptide was found in rats exposed to moderate chronic hyperoxia. The apparent molecular weight of this collagen fraction suggests that it is a product of collagen type I cleavage by a rodent-type interstitial collagenase (MMP-13). We conclude that chronic moderate hyperoxia and recovery from chronic hypoxia have a similar effect on collagenous proteins of the peripheral pulmonary arterial wall.

FT-Raman Spectroscopy: A Tool for Monitoring the Demineralization of Bones

A nondestructive analytical method based on the use of Fourier transform Raman spectroscopy (FT-RS) for identification and quantitative analysis of hydroxyapatite (HAP) and collagen (COL) in bones was developed. A calibration curve based on the Raman spectra of known powder mixtures of HAP–COL was constructed with the use of the Raman bands at 960 cm−1 for HAP and 2937 cm−1 for COL. It was found that I960 /I2937 = 0.46/ WC — 0.36, where I960 and I2937 are the relative intensities for the 960 and 2937 cm−1 Raman bands, respectively, and Wc represents the weight fraction of collagen. The detection limit for HAP and COL was found to be 2.8 and 0.6 wt %, respectively. The potential of using RS for an in vitro point-by-point analysis (“mapping”) of bones was demonstrated successfully on an artificially demineralized ox femur sample.

Effect of Ac-SDKP on Cardiac and Renal Collagen Deposition in Aldosterone-Salt Hypertension

62 Ac-SDKP is a natural substrate for the N-terminal active site of ACE. We have data showing that Ac-SDKP inhibits collagen synthesis both in vitro and in vivo . In the present study, we tested whether Ac-SDKP prevents cardiac and renal fibrosis in a renin-independent model of hypertension (aldosterone-salt) characterized by renal and cardiac fibrosis. Uninephrectomized adult SD rats were divided into 3 groups: control (saline) and aldosterone-salt (18 μg/d) alone or combined with Ac-SDKP 800 μg/kg/d.Saline, aldosterone or Ac-SDKP was given s.c. via osmotic pump for 6 weeks. We found that Ac-SDKP decreased collagen content (hydroxyproline assay) in the LV, right ventricle (RV) and kidney, and LV collagen fraction, with no significant effect on BP and LV hypertrophy (Table). Our results suggest that Ac-SDKP prevents cardiac and renal fibrosis in renin-independent hypertension. This indicates that Ac-SDKP could participate in the antifibrotic effect of ACEi, since ACEi inhibit fibrosis in this model of hypertension and markedly increase plasma Ac-SDKP.

Effect of Ac-SDKP on Cardiac and Renal Collagen Deposition in Aldosterone-Salt Hypertension

62 Ac-SDKP is a natural substrate for the N-terminal active site of ACE. We have data showing that Ac-SDKP inhibits collagen synthesis both in vitro and in vivo . In the present study, we tested whether Ac-SDKP prevents cardiac and renal fibrosis in a renin-independent model of hypertension (aldosterone-salt) characterized by renal and cardiac fibrosis. Uninephrectomized adult SD rats were divided into 3 groups: control (saline) and aldosterone-salt (18 μg/d) alone or combined with Ac-SDKP 800 μg/kg/d.Saline, aldosterone or Ac-SDKP was given s.c. via osmotic pump for 6 weeks. We found that Ac-SDKP decreased collagen content (hydroxyproline assay) in the LV, right ventricle (RV) and kidney, and LV collagen fraction, with no significant effect on BP and LV hypertrophy (Table). Our results suggest that Ac-SDKP prevents cardiac and renal fibrosis in renin-independent hypertension. This indicates that Ac-SDKP could participate in the antifibrotic effect of ACEi, since ACEi inhibit fibrosis in this model of hypertension and markedly increase plasma Ac-SDKP.

Effects of dietary xylitol on collagen content and glycosylation in healthy and diabetic rats

The effects of three-month dietary xylitol supplementation on the amounts and hexose contents of acid-soluble collagen as well as on the amounts and fluorescence of collagenase-soluble collagen were studied in healthy and streptozotocin-diabetic male rats. Collagen was extracted from skin samples. In the healthy rats, supplementation with xylitol (10%) increased the hydroxyproline content of the acid-soluble fraction and skin thickness. In diabetic rats receiving and not receiving xylitol, the acid-soluble collagen fraction was markedly lower than in healthy rats. However, its amount was significantly elevated when xylitol had been added to the diet. Supplementation with xylitol caused no changes in the amounts of collagenase-soluble fraction in either healthy or diabetic rats. Supplementation with xylitol (10%) significantly decreased the hexose content of acid-soluble collagen and the fluorescence of the collagenase-soluble fraction in both healthy and diabetic rats. The results indicate that dietary xylitol affects collagen synthesis and collagen glycosylation.

Immunochemical and Immunohistochemical Identification of a Minor Collagen in Raw Muscles of Decapod Mollusks

ABSTRACT: Approximately 10% of total muscle collagen in 6 decapod molluskan species was recovered as minor collagenous fractions by limited pepsin digestion and differential salt precipitation. The main alpha components (α1) in these fractions showed similar peptide maps of V-8 protease and lysyl endopeptidase digests to each other and had reactivity to the antiserum against the al component of the minor collagen (named Type SQ-II) from Todarodes pacificus muscle in immunoblot analysis. These results suggested that the minor molecular species of collagen corresponding to Type SQ-II of Todarodes pacificus was widely distributed in the mantle muscle of decapod mollusks. In addition, immunohistochemical experiments revealed that Type SQ-II collagen distributed mainly in intramuscular thin connective tissue (endomysium), suggesting the functional importance of this molecule to the development of meat texture of decapod mollusks.

Effect of dietary catechin and Spirulina on vitamin C metabolism in red sea bream

SUMMARY: The zero-year red sea bream Pagrus major were fed for 41 days on dry pellets containing 1% Teaflan (60% catechin) or Spirulina supplement. The effects of catechin and Spirulina on ascorbate absorption, lipid metabolism, and collagen synthesis were compared in relation to vitamin C nutrition. Total ascorbate concentrations in the serum and liver were increased significantly in the catechin-fed groups relative to the control, but Spirulina increased in value only in liver. Feeding with catechin and Spirulina depressed non-esterified fatty acid and total lipid in serum, respectively. Liver lipid was depressed by feeding catechin and Spirulina. Hepatic free carnitine and long-chain acylcarnitine contents were markedly higher in both catechin- and Spirulina-fed groups than in the controls. Hepatic carnitine palmitoyltransferase activity was markedly elevated in the Spirulina-fed group. In contrast, glucose-6-phosphate dehydrogenase and fatty acid synthase activities were not different among the groups. The collagen fraction soluble at 20°C was lower and the insoluble collagen fraction (not soluble at 70°C) was higher in catechin- and Spirulina-fed groups. These results suggest that dietary supplementation with catechin, as well as Spirulina, improved vitamin C metabolism in young red sea bream.

Modification of native collagen reduces antigenicity but preserves cell compatibility

Porcine intestinal collagen (ICL), derived from processed small intestine, is used as a part of a remodelable bilaminate biosynthetic vascular prosthesis. The process for the production of ICL involves mechanical cleaning of non-crosslinked porcine intestine (NC-ICL), disinfection with peracetic acid (PA-ICL), and crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (PA/EDC-ICL). Two model systems were investigated to evaluate the effect of these agents on the humoral response to NC-ICL. First, the antibody titers of rabbits immunized with NC-ICL, PA-ICL, and PA/EDC-ICL were determined, and second, the humoral response of canines receiving collagenous vascular implants was examined. Collagenous and noncollagenous fractions were extracted from NC-ICL, PA-ICL, and PA/EDC-ICL and separated by SDS-PAGE. PA and EDC treatment decreased the number of extractable proteins as compared to NC-ICL. Immunoblot techniques demonstrated anti-NC-ICL antibodies recognized multiple immunoreactive proteins in NC-ICL, but not in PA-ICL or PA/EDC-ICL; and rabbits immunized with NC-ICL produced higher antibody titers to ICL proteins than rabbits immunized with either PA-ICL or PA/EDC-ICL. It was, therefore, apparent that NC-ICL was more antigenic than either PA-ICL or PA/EDC-ICL. The humoral immune response of canines to PA/EDC-ICL fabricated vascular grafts was determined. At 4 weeks, 8 weeks, and 12 weeks postimplant, serum antibodies to ICL proteins or type I collagen could not be detected. These data demonstrate a reduced humoral immune response to PA/EDC-ICL. (c) 1996 John Wiley & Sons, Inc.

Regression of Chronic L -NAME-Treatment-induced Left Ventricular Hypertrophy: Effect of Captopril

Long-term administration of NG-nitro- L -arginine methyl ester (L -NAME) induces development of NO-deficient hypertension and left ventricular (LV) hypertrophy. In this work, we examined the effect of spontaneous and captopril-induced recovery on LV hypertrophy and protein composition in rats with developed L -NAME-induced hypertension. Four groups of rats were investigated: control L -NAME 40 mg/kg/day for 4 weeks (L -NAME) L -NAME 40 mg/kg/day for 4 weeks followed by 3-week spontaneous recovery (L -NAME+R) L -NAME 40 mg/kg/day for 4 weeks followed by 3 weeks of captopril treatment at a dose of 100 mg/kg/day (L -NAME+C). LV hypertrophy in the L -NAME group was associated with an increase in content and concentration of left ventricular DNA and RNA, concentration of metabolic proteins (MP) and soluble collagenous proteins (SCP). Spontaneous recovery period reduced the hypertension, without regression of LV hypertrophy. Left ventricular DNA and RNA content were increased in the L -NAME+R group. In this group, concentrations of MP, contractile proteins (CP), and collagenous proteins did not differ from those in the L -NAME group. Captopril treatment caused total regression of hypertension and LV hypertrophy and decreased both content and concentration of DNA and RNA, as well as the contents of MP, CP and SCP v the L -NAME group. However, after captopril treatment, concentration of collagenous and non-collagenous protein fractions remained increased v control. We conclude that spontaneous regression of L -NAME-induced hypertension is not associated with regression of LV hypertrophy. LV hypertrophy was regressed only in captopril-treated animals.

Role of kinins in chronic heart failure and in the therapeutic effect of ACE inhibitors in kininogen-deficient rats.

Using Brown Norway Katholiek (BNK) rats, which are deficient in kininogen (kinin precursor) due to a mutation in the kininogen gene, we examined the role of endogenous kinins in 1) normal cardiac function; 2) myocardial infarction (MI) caused by coronary artery ligation; 3) cardiac remodeling in the development of heart failure (HF) after MI; and 4) the cardioprotective effect of angiotensin-converting enzyme inhibitors (ACEI) on HF after MI. Two months after MI, rats were randomly treated with vehicle or the ACEI ramipril for 2 mo. Brown Norway rats (BN), which have normal kininogen, were used as controls. Left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), end-diastolic pressure (EDP), and ejection fraction (EF) as well as myocardial infarct size (IS), interstitial collagen fraction (ICF), cardiomyocyte cross-sectional area (MCA), and oxygen diffusion distance (ODD) were measured. We found that 1) cardiac hemodynamics, function, and histology were the same in sham-ligated BN and BNK rats; 2) IS was similar in BN and BNK; 3) in rats with HF treated with vehicle, the decrease in LVEF and the increase in LVEDV, LVESV, LVEDP, ICF, MCA, and ODD did not differ between BNK and BN; and 4) ACEI increased EF, decreased LVEDV and LVESV, and improved cardiac remodeling in BN-HF rats, and these effects were partially blocked by the bradykinin B(2) receptor antagonist icatibant (HOE-140). In BNK-HF rats, ACEI failed to produce these beneficial cardiac effects. We concluded that in rats, lack of kinins does not influence regulation of normal cardiac function, myocardial infarct size, or development of HF; however, kinins appear to play an important role in the cardioprotective effect of ACEI, since 1) this effect was significantly diminished in kininogen-deficient rats and 2) it was blocked by a B(2) kinin receptor antagonist in BN rats.

Left ventricular remodeling and chronic heart failure after myocardial infarction in mice

Today, various kinds of knock out or transgenic murine models enabled us to extend our murine research. This study was designed to establish the murine model of LV remodeling and heart failure after myocardial infarction. We induced myocardial infarction in 197, 8 to 9 weeks old male C57BL/6 mice. 24 hours, 3 days, and 1,2, 4, 8, 12, and 20 weeks after operation, groups of 4 or 5 mice each underwent echocardiographic study and were then sacrificed. Total heart, wet and dry lung weights were measured. Interstitial collagen deposition level were histologically measured using a computerized morphometdc system. The infarction area involved 57% of the left ventricle (LV) on average, and the mortality rate within 24 hours after operation was 53%. 17 out of 65 mice died of cardiac rupture within 8 days of coronary occlusion. Left ventricular end-diastolic diameter (LVEDd) increased from 3.4_+0.14 mm to 7.1_+0.59 mm (p<0.O01). Total heart and lung weights increased from 101+10 mg to 237_+34 mg (p<0.001), and from 147_+9.1 mg to 419-+55 mg, respectively (p<0.001). The wet/dry lung weight ratio increased from 4.49_+0.87 to 9.29_+0.31 (p<0.001). Volume collagen fraction increased from 0.64_+0.27% to 9.38_+0.63%. (p<0.001) In this murine model, the increase of wet/dry lung weight ratio was consistent with the development of chronic heart failure. It represents a promising experimental tool to study the molecular and biochemical mechanisms of LV remodeling and heart failure.