Vitamin D restriction enhances periovarian adipose tissue inflammation in a model of menopause

Background: Menopause and deficiency in vitamin D (VD) are two health problems usually associated with aging women.Objective: We aimed to study inflammation in visceral adipose tissue when bilateral ovariectomy is combined with dietary restriction in VD.Methods: We studied 60 female C57BL/6 mice 3 months of age. Half of the animals had bilateral ovariectomy (Ovx group, n = 30) and half a sham procedure (Control [C] group, n = 30), and half of each Ovx or C group were fed a standard diet containing VD or a diet restricted in VD (D-) for an additional 12 weeks. Therefore, four groups were formed (n = 15 each group): C, C(D-), Ovx, and Ovx(D-). After sacrifice, the periovarian adipose tissue (PAT) was investigated.Results: In PAT, we observed different levels of hypertrophied adipocytes, enhanced proinflammatory cytokines, activation of inflammatory markers, and components of the extracellular signal-regulated kinase. The most affected PAT was seen in the Ovx(D-) group, followed by the Ovx group, the C(D-) group, and the C group (the least altered).Conclusion: The results demonstrate that ovariectomy and dietary restriction of VD are inducers of adverse effects on mouse visceral adipose tissue. When combined, these insults might enhance PAT inflammation.

Assessment of Spleen Filtrate Function in Renal Transplant Recipients Using Technetium-99m Stannous Colloid Liver-Spleen Scan

BACKGROUND

Functional hyposplenism (FH) is indicated by an anatomically present spleen that fails to take up radiolabeled colloid. The occurrence of FH has been reported in a small group of renal transplant recipients based on hematologic parameters. The aim of this study was to replicate this association in a larger group of renal transplant recipients with the use of technetium-99m-stannous colloid liver-spleen scan to assess the spleen function.

METHODS

This survey based on single samples enrolled 101 unselected adult patients with functional kidney grafts >180 days after transplantation. All patients underwent ^99mTc-stannous colloid scan to assess spleen function as well as bone marrow uptake of radiocolloid along with an anatomic and blood flow study of the spleen and kidney with the use of Doppler sonography.

RESULTS

The prevalence of hyposplenism was 32.7% (33/101) for the cohort, and increased uptake of radiocolloid by the bone marrow was seen in 9.9% (10/101). According to the multivariate analysis, the frequency of hyposplenism was significantly influenced by indirect bilirubin and hemoglobin, and direct bilirubin and neutrophil count remained as independent predictors of bone marrow uptake.

CONCLUSIONS

This study demonstrated that a group of renal transplant recipients has FH. In addition, bone marrow uptake might be interpreted as liver dysfunction. In this situation, the small amount of contrast (spleen compared with liver) would leave hyposplenism undiagnosed. Further prospective and longitudinal clinical studies are needed to determine the clinical impact of this condition on the management of renal transplant recipients.

High fat diets modulate nitric oxide biosynthesis and antioxidant defence in red blood cells from C57BL/6 mice

The consumption of a high fat (HF) diet is considered a risk factor for the development of obesity. On the other hand, a monounsaturated HF diet has beneficial cardiometabolic effects. Since nitric oxide (NO) modulates vascular homeostasis, we investigate whether HF diets that vary in fatty acid composition have a different effect on theL-arginine-NO pathway and oxidative stress in C57BL/6 mice red blood cells (RBC). The olive oil diet induced an activation of L-arginine transport compared to other diets. NO synthase (NOS) activity was increased in all unsaturated HF diets (olive, sunflower and canola oils). Moreover, the expression of endothelial NOS (eNOS) and inducible NOS (iNOS) was increased in the olive oil group. In contrast, NOS activity from the lard group was decreased associated with diminished l-arginine transport. Olive oil also induced superoxide dismutase activation. Inhibition of the L-arginine-NO pathway in the lard group could contribute to cardiovascular diseases, while unsaturated HF diets may have a protector effect via enhanced NO bioavailability.

Allopurinol attenuates L-NAME induced cardiomyopathy comparable to blockade of angiotensin receptor

It is widely recognized that L-NAME exposed rats develop myocardial fibrosis and hypertrophy. The aim of this study was to evaluate the contribution of xanthine oxidase (XO) to these phenomena using allopurinol, isolated or associated with olmesartan. Thirty adult male Wistar rats were divided into 5 groups (n=6) and studied for 5 weeks: L group (L-NAME, 40mg/kg/day); L+A group (L-NAME and allopurinol, 40 mg/kg/day); L+O group (L-NAME and olmesartan, 15mg/kg/day); L+A+O group (L-NAME, allopurinol, and olmesartan); and control group. L-NAME caused arterial hypertension and cardiomyocyte hypertrophy. Hypertension was prevented by olmesartan, but not by allopurinol. There was an increase of left ventricular mass index in the L-NAME group that was prevented by allopurinol, olmesartan and by the combination of both. The increase in mean cardiomyocyte transversal area caused by L-NAME was prevented by the allopurinol and olmesartan combination, or by olmesartan used as monotherapy, but not by allopurinol alone. There was a reduction in the myocardial vascularization index caused by L-NAME which was abolished by allopurinol or by olmesartan, but not by the association. L-NAME caused a reduction in the total number of cardiomyocyte nuclei. This was prevented by olmesartan alone or associated with allopurinol, but not by allopurinol alone. We conclude that XO has an important contribution to adverse cardiac remodeling in L-NAME exposed animals. Moreover, allopurinol acts without interfering with L-NAME induced hypertension. The protective action of this drug is comparable to the results obtained with olmesartan. Antioxidative mechanisms are proposed to account for the pressure independent effects of allopurinol.

Pineal Gland Post-natal Growth in Rat Revisited

We studied the pineal gland (PG) growth separating two critical moments of the rat post-natal development: the lactation and post-weaning periods. We studied 30 Wistar rats in the post-natal day - PN day 6, 10, 21, 45, 60 and 90 using light microscopy and quantitative methods (allometry and stereology). We estimated the PG volume (using the Cavalieri's principle) and the number of pineal gland cell nuclei (PGCN, using the disector method). We analysed the correlation of the PG volume (y) versus brain weight (x) in the different age groups (the bivariate study used log-transformed data and the allometric model log y = log a + b log x). The PG growth gradually decelerated in older rats than in younger rats. The major increment of the PG growth was observed between PN day 6 and PN day 10, while the minor increment was observed after weaning between PN day 45 and PN day 60. After 60 days of age differences were no more observed. The relative growth of the PG was allometrically positive in all age groups, and growth curves separated the lactation from the after weaning periods. The number of PGCN of rat continuously increased during post-natal life and differences between the lactation and after weaning periods were significant. It is possible that the supporting cells, fibres and new synapses are responsible for that PG late post-natal increase.

Amlodipine preserves the glomerular number in spontaneously hypertensive rats

The calcium channel blockers have individual pharmacological and therapeutic properties that may vary, but as a group, they are effective antihypertensive agents in patients with renal disease. Their effects on the kidney may extend beyond BP reduction alone. Fifteen one-year-old male spontaneously hypertensive rats (SHR) were separated in three groups: Initial control group (IC), Final control group (FC, SHR received standard rat chow and fresh water ad libitum during 15 weeks), Amlodipine group (Aml, SHR) received 0.2 mg/kg/day of amlodipine in addition to food and water during 15 weeks. The glomerular number was estimated using the disector method. In the Control group, the BP level increased almost 20 per cent in the first six weeks (from 186 +/- 11 to 223 +/- 16 mmHg, p<0.01) and then BP level increased almost 15 percent until week 15 (from 223 +/- 16 to 258 +/- 20 mmHg, p<0.01). In the same period, the Aml group showed a progressively low BP, reaching a level almost 50 per cent lower in the week 15 than in the week 1 (from 190 +/- 15 to 101+/-8 mmHg, p<0.01). Amlodipine treatment significantly decreased the serum creatinine, more than 12 per cent lower than the FC group (from 70.4 +/- 6.2 to 61.4 +/- 5.2 micromol/L, p<0.05). However, proteinuria was not different when groups were compared. The FC group reached a glomerular number almost 20 percent smaller than the IC and Aml groups (from 35 x 10(3) +/- 7 x 10(3) in IC group, 34 x 10(3) +/- 4 x 10(3) in Aml group to 27 x 10(3) +/- 3 x 10(3) in FC group, p<0.05). A possible protective effect of amlodipine against the loss of glomeruli in SHR is a major additional action of amlodipine in the treatment of hypertension mainly when the renal lesion already exists.

Leprosy: contribution of mast cells to epineurial collagenization

BACKGROUND

Leprosy, a disease caused by Mycobacterium leprae, is an important health problem worldwide. It is responsible for an irreversible nerve damage in which fibrosis plays an important role. The existence of an interaction between mast cells and different fibrotic conditions has long been observed. Tryptase, the most abundant protein product of human mast cells, has been shown to be mitogenic for fibroblasts and to increase type I collagen production.

PATIENTS AND METHODS

In order to explore the possible relationship between tryptase-rich mast cells and nerve fibrosis in leprosy, we studied 24 sural nerve biopsies of patients with leprous neuropathy. Mast cells stained with mouse antihuman mast cell antitryptase clone AA1 as well as fibrosis, were quantitatively estimated in both epi- and endoneurial compartments.

RESULTS

There was a remarkable association between collagen increase and tryptase-rich mast cell density in the epineurium but not in the endoneurium of leprous nerves.

CONCLUSION

Since the epineurium in leprosy is type I collagen rich, the present findings support a tryptase-rich mast cell contribution to epineurial collagenization in leprosy through their tryptase secretion.

Different edible oil beneficial effects (canola oil, fish oil, palm oil, olive oil, and soybean oil) on spontaneously hypertensive rat glomerular enlargement and glomeruli number

We have tested the different edible oil effects on the blood pressure (BP) control and the following glomerular protection. Six groups of 12-week-old male spontaneously hypertensive rats (SHR) (n = 5), have received different edible oils (fish, canola, palm, olive, and soybean) or a placebo by gavage for 13 weeks. Renal cortex was analyzed through light microscopy and stereology. Usual BP increase, glomerulosclerosis, glomerular enlargement, and glomeruli loss in SHR has been prevented (fish, canola and palm oils) or attenuated (olive and soybean oils) by these oil long-term administration. The most favorable effect has been seen in the fish oil administration (source of n-3 polyunsaturated fatty acids, PUFA, eicosapentaenoic and docosahexaenoic acids), followed by both canola and palm oils (source of n-3 PUFA plus n-9 monounsaturated, MUFA, and saturated fatty acid, respectively), and finally both olive and soybean oils (source of n-9 MUFA and n-6 PUFA, respectively).

Malnutrition during lactation in rats is associated with higher expression of leptin receptor in the pituitary of adult offspring

OBJECTIVE

Recent studies have shown that leptin receptor is expressed in human and rat pituitary glands. The expression of leptin receptor in rats whose dams were malnourished during lactation has not been previously reported.

METHODS

We examined leptin receptor expression in the pituitary gland of adult rats whose dams were assigned to one of the following groups during lactation: control diet, protein-restricted diet (8% protein), or energy-restricted diet (the control diet fed in restricted quantities that were calculated according to the mean ingestion of the protein-restricted group). After weaning, all pups had free access to the control diet until they reached adult age, at which time leptin receptor expression in the pituitary was analyzed by immunohistochemistry.

RESULTS

Adult animals from protein- and energy-restricted dams had a higher expression of leptin receptor in pituitary tissue, normal serum leptin concentrations, higher serum tri-iodothyronine concentrations, and lower thyroid-stimulating hormone concentrations than did the control rats.

CONCLUSIONS

In the fed state, leptin has a stimulatory effect on release of thyroid-stimulating hormone. The higher expression of leptin receptor in the pituitary of animals from protein- and energy-restricted dams may suggest a postreceptor failure in leptin action. This higher receptor expression may have allowed a greater inhibition of release of thyroid-stimulating hormone.

Stereology of the liver in three species of Leontopithecus (Lesson, 1840) Callitrichidae--primates

Studies on liver morphology and stereology are relevant to the comparative anatomical and pathological research. They also facilitate the use of non-human primates in basic research, which has substantially supported studies in human medicine. Quantitative studies of liver structures have also been more extensive in Old World primates and other vertebrates. Twenty-three livers of adult lion tamarins were studied (six Leontopithecus rosalia, seven Leontopithecus chrysomelas, and 10 Leontopithecus chrysopygus), dissected, and fixed in 10% neutral buffered formalin solution. For stereological quantification, the liver was regarded as consisting of parenchyma (hepatocytes) and stroma (non-hepatocytes). The volume density (V(v)) was determined by point counting, and the disector method was used to obtain the numerical density of hepatocytes (N(v)). Hepatic stereological differences among the three species of lion tamarins were not statistically significant. Therefore, the pooled V(v[hepatocyte]) and V(v[stroma]) could be determined as 96.2 and 7.4%, respectively, and N(v[hepatocyte]) as 500.33 x 10(6) cm(-3). Significantly different, the values found for V(v[hepatocyte]) and N(v[hepatocyte]) in lion tamarins were, respectively, 0.09 and 2.8 times greater than those in baboons, and 0.17 and 3.8 times greater than those in man. However, the V(v[stroma]) was 1.04 times smaller than that in baboons and 1.79 times smaller than that in man.

Effect of telmisartan on preexistent cardiac and renal lesions in spontaneously hypertensive mature rats

Fifteen adult male spontaneously hypertensive rats (one year old) (SHR) were separated into three groups (n=5 each) during 15 weeks as follows: initial control group (IC); final control group (FC); and telmisartan group (T) (1.2 mg/kg/day of telmisartan). Serum and urinary creatinine and proteinuria were not different comparing untreated and telmisartan-treated SHRs. FC rats showed a continuous BP increase during the study while T rats reached the 15th week with a significantly low BP. The LV mass index was significantly smaller in the T group than in the FC group, as was the glomerular hypertrophy. The cardiomyocyte nuclei density per area and the cardiomyocyte mean cross-sectional area were smaller in the T group than in both the IC and FC groups. Intramyocardial artery densities (per area and per volume) were greater in the T group than in untreated SHRs, but myocardial fibrosis was reduced. In conclusion, telmisartan monotherapy effects on BP and also on the hypertension target organs, heart and kidney, are favorable. Telmisartan is able to attenuate SHR cardiomyocyte and glomerular hypertrophies, and myocardial reactive fibrosis as well. It also is favorable to the intramyocardial microcirculation.

Stereology of the myocardium in Leontopithecus (Lesson, 1840) callitrichidae - primates

Rare morphological features of the Leontopithecus cardiovascular system have been reported in the literature. The samples analyzed in this study came from 33 specimens of Leontopithecus from the collection of the Center of Primatology of Rio de Janeiro-FEEMA (CPRJ-FEEMA). Morphometry and stereological data were obtained from all animals. Adult body weights of L. rosalia were the lowest, the greatest being those of L. chrysopygus caissara; body weights of L. chrysomelas and L. c. chrysopygus were similar and in between those of the two former species. Cardiomyocytes (left ventricular myocardium) were bigger in adults than in infants. The myocardium of L. rosalia showed focal fibrosis, fatty vacuoles, and hyalinization. In L. chrysomelas the myocardium showed areas of fibrosis and presence of mononuclear cells. Fibrosis and areas of congestion were observed in L. c. chrysopygus; areas of disorganization and vascular congestion were found in L. c. caissara. In L. rosalia infants, a greater density of vessels per myocardial area and a greater length density of vessels were observed as compared with those of L. chrysomelas. In adults, L. chrysomelas showed greater density of connective tissue in the myocardium than L. c. chrysopygus and L. c. caissara did. In L. rosalia, cardiomyocyte nuclei had a greater area density than those of the other forms of Leontopithecus. These characteristics may explain the faster development of L. rosalia infants as compared with that of L. chrysomelas and L. c. chrysopygus kept under the same handling conditions at the CPRJ-FEEMA.

The effect of ovariectomy and estradiol replacement on collagen and elastic fibers in the bladder of rats

The authors quantified the collagen and elastic fibers in the bladder wall of ovariectomized rats with and without estradiol replacement. This study was conducted on 60 3-month-old Wistar rats. Group 1 remained intact; group 2 underwent bilateral ovariectomy and were sacrificed after 30 days; group 3 were sham operated and sacrificed after 30 days; group 4 had a bilateral ovariectomy and after 30 days were started on subcutaneous injections of 17beta-estradiol (10 microg/kg body weight) for 90 days; group 5 were sham operated and after 30 days were on started subcutaneous sesame oil replacement (0.2 ml/day) for 90 days; group 6 had a bilateral ovariectomy and after 30 days were started on subcutaneous sesame oil replacement (0.2 ml/day) for 90 days. Sirius red and Weigert's resorcin-fuchsin were used to stain collagen and elastic fibers on paraffin-embedded rat bladder sections. The M-42 grid system was used to quantitatively analyze the fibers. Ovariectomy had no effect on the volumetric density and absolute volume of the collagen and elastic fibers in the bladder wall of rats, or on the weight of the bladder. Estradiol replacement in castrated animals did not demonstrate any significant difference in the stereological parameters compared to the castrated group without hormonal replacement.

Beneficial effect of enalapril in spontaneously hypertensive rats cardiac remodeling with nitric oxide synthesis blockade

AIMS

To study the efficiency of an angiotensin converting enzyme inhibitor on the blood pressure (BP) and the myocardium remodeling when spontaneously hypertensive rats (SHRs) are submitted to nitric oxide synthesis (NOs) blockade (with L-NAME) and simultaneously treated.

METHODS

Young adult male SHRs were separated in four groups (n = 5) and treated for 20 days: Control, L-NAME, L-NAME+Enalapril, and Enalapril. The alterations of the BP, heart mass/body mass ratio and stereological parameters for myocytes, connective tissue and intramyocardial vessels were studied among the groups.

RESULTS

The SHRs with NOs blockade showed a great modification of the myocardium with extensive areas of reparative and interstitial fibrosis and accentuated hypertrophy of the cardiac myocytes (cross sectional area 60% higher in animals taking L-NAME than in Control SHRs). Comparing the SHRs with NO deficiency (L-NAME group), the Control SHRs and the Enalapril treated SHRs significant differences were found in the BP and in all stereological parameters. The NO deficiency caused an important BP increment in SHRs that was partially attenuated by Enalapril. This Enalapril effect was more pronounced in Control SHRs. A significant increment of the intramyocardial vessels was observed in NO deficient SHRs and Control SHRs treated with Enalapril demonstrated by the stereology (greater microvascular densities in treated SHRs).

CONCLUSION

Enalapril administration showed a beneficial effect on vascular remodeling and myocardial hypertrophy in SHRs. In SHRs with NO blockade, however, the beneficial effect of Enalapril occurred only in vascular remodeling.

Myocardial changes after spironolactone in spontaneous hypertensive rats. A laser scanning confocal microscopy study

The present study aims to objectivate by laser scanning confocal microscopy, the cardiac structure of the spontaneously hypertensive rats (SHR) treated with different doses of spironolactone, either alone or in combination with an angiotensin converting enzyme inhibitor or with a calcium channel blocker. Thirty SHRs were divided into six groups and treated during 13 weeks as follows: control, spironolactone (5, 10 and 30 mg/kg/day), spironolactone + enalapril and spironolactone + verapamil. Spironolactone action on the SHR blood pressure (BP) was dose-dependent. The cardiac hypertrophy was affected by the treatment with spironolactone (high dose) or a combination of spironolactone and Enalapril. The myocardial structure was less affected by the spironolactone monotherapy (at all doses) showing hypertrophied cardiac myocytes, focal areas of the reactive fibrosis, inflammatory infiltrate. The treatment with spironolactone in combination with enalapril or verapamil prevented these alterations. In conclusion, the monotherapy with spironolactone had only a limited effect in the preservation of the myocardial structure and in the attenuation of the interstitial fibrosis in SHRs, even after high dose. This action on the myocardium is more efficient when the spironolactone (even in medium dose) was associated with enalapril or verapamil.

Myocardial stereological adaptations in wistar rats fed with different high-fat diets during 18 months

This study has the purpose of investigating the influence of different high-fat experimental diets on myocardial structure in rats. Twenty-seven male rats were fed from 21 d old (postnatal age) until 18 mo old with one of the following supplemented diets: soybean oil (S) (n= 6), canola oil (CA) (n= 8), or lard and egg yolk (LE) (n= 6) or canola oil+ lard and egg yolk (CA+LE) (n=7). The blood pressure (BP) was measured, and after the sacrifice the cardiac biometry and the myocardial stereology were determined: cross-sectional area of cardiomyocyte (A), volume density (Vv), surface density (Sv), and length density (Lv) in relation to the cardiomyocytes (cm), connective tissue (ct), and blood vessels (v). The CA group rats had lower BP, A[cm], and Vv[ct]; they had greater Vv[cm], Sv[cm], Vv[v], Lv[v], and Sv[v] than the other groups. The S rats had intermediary values for the myocardium and blood vessel parameters between the CA and LE group rats. These results support the notion that the long-term use of canola oil in the diet is better to preserve the myocardium structure, including microvascularization, than soybean oil or lard and egg yolk.

Stereology of cardiac hypertrophy induced by NO blockade in rats treated with enalapril and verapamil

OBJECTIVE

To quantify the structural myocardial response when chronic NO blockade hypertension is treated with antihypertensive drugs.

STUDY DESIGN

Four groups of 10 male Wistar rats each were separated as follows: control, L-arginine-methyl-ester (NAME), L-NAME + angiotenisin-converting inhibitor (enalapril), L-NAME + calcium channel blocker (verapamil). All animals' blood pressure (BP) was measured weekly. After 40 days of experimentation the heart mass/body mass ratio (HBR) was determined, and the volume densities of the cardiac components were shown by stereology (Vv[c] for cardiomyocytes, Vv[i] for cardiac interstitium and the mean cross-sectional area of cardiomyocytes, a[c]).

RESULTS

Significant differences by comparison with the control group were: BP increased 71% and HBR increased 24% in the L-NAME group. Vv[c] was 15% smaller in L-NAME animals, while an increase of 11% occurred in the enalapril group and 7% in the verapamil group. Vv[i] increased 20% in the L-NAME group; however, it decreased 13% in the enalapril group and 10% in the verapamil group. a[c] Was 30% greater in the L-NAME group, 13.5% in the enalapril group and 8.5%, in the verapamil group. a[c] Was 12.5% smaller in the enalapril group and 16% smaller in the verapamil group when L-NAME rats were compared.

CONCLUSION

Stereology revealed an equivalent effect of enalapril and verapamil in reducing BP, cardiomyocyte hypertrophy and interstitial fibrosis in rats with NO synthesis blockade after six weeks of treatment.

Renal cortical remodelling by NO-synthesis blockers in rats is prevented by angiotensin-converting enzyme inhibitor and calcium channel blocker

The cortical remodelling was studied when chronically nitric oxide synthesis (NOs) blockade (L-NAME-induced) hypertensive rats are simultaneously treated, or not, with angiotensin-converting enzyme inhibitor or calcium channel blocker. Four groups of eight rats each were studied as follows: Control (C), L-NAME (L), L-NAME+Enalapril (L+E) and L-NAME+Verapamil (L+V). The systolic blood pressure (SBP) was weekly recorded. The cortex of the left kidneys was analysed according to the vertical section design. The volume-weighted mean glomerular volume (VWGV) was made through the "point-sampled intercepts" method. Enalapril and verapamil were efficient in reducing the SBP in rats submitted to NOs blockade. Glomeruli had considerable alterations in L group rats (glomerular hypertrophy or sclerosis) and tubular atrophy. The VWGV was 100% greater in L group rats than in the C group rats, while it was 30% smaller in L+E and L+V groups than in L group. The tubular volume was 30-50% greater, while the tubular length was 20-30% smaller in the L group than in the other groups. The renal cortical region showed glomerular sclerosis/hypertrophy and tubular remodelling in rats with NOs blockade that was efficiently prevented with the simultaneous treatment with enalapril or verapamil.

Effect of different high-fat diets on the myocardium stereology and blood pressure in rats

The effect of three high-fat diets containing 29% canola oil (CA), lard plus egg yolk (LE) or canola oil, lard and egg yolk (CA+LE) in male Wistar rats was investigated over a period of 6 months. We analyzed the myocardium, composed of cardiomyocytes and interstitium, which is made up of connective tissue and blood vessels. Volume density of cardiomyocyte (Vv[m]), volume density of blood vessels (Vv[v]), and volume density of connective tissue (Vv[ct]) were the stereological parameters determined. The rats of the LE group had a significantly higher heart mass/body mass ratio than those of the CA group. The blood pressure of the LE group was significantly higher than that of the other groups. In the CA group, the Vv[m] was significantly higher and the Vv[ct] was significantly lower than in the other groups. The myocardium of both the LE and CA+LE groups showed a significant reduction of Vv[m] and a compensatory increase of the Vv[ct]. These findings were less pronounced in the CA+LE group, in which the Vv[v] was found to be significantly higher than in the CA group. Comparing three high-fat diets, the data suggest that the diet canola oil had a major beneficial effect, preserving the myocardial structure and the blood pressure in rats.

Heart biometry and allometry in rats submitted to nitric oxide synthesis blockade and treatment with antihypertensive drugs

Fifty mature male rats were separated into groups of ten rats each (control, L-NAME, spironolactone, enalapril and verapamil). On the 41st day of experimentation, animals were anesthetized, weighed and sacrificed. The tail blood pressure (TBP) was 76% higher in L-NAME group than in the control group. Spironolactone, enalapril and verapamil were efficient in reducing TBP in those respective groups of rats (spironolactone was less efficient in reducing TBP). The heart mass/body mass ratio (HBR) increased 24% in L-NAME group and spironolactone group. No differences in HBR were found when control animals and animals treated with enalapril and verapamil were compared. Heart volume (HV) was greater in L-NAME group than other groups, but it was not different comparing the L-NAME and the spironolactone groups. The left ventricle was responsible for the changes in the HV. The relationship between the HV and the body mass (BM) was not significant in the groups L-NAME and spironolactone. However, this relationship was significant and allometric in control, enalapril and verapamil groups. In control group, HV had a positive allometric tendency against the BM, but in the enalapril and verapamil groups this tendency was allometrically negative. Cardiac hypertrophy in rats under inhibition of NO synthesis was prevented by treatment with enalapril and verapamil more efficiently than spironolactone.

Volume-weighted mean nuclear volume and numerical nuclear density in the cardiomyocyte following enalapril and verapamil treatment

The estimation of the volume-weighted mean nuclear volume, nu(nu), and the numerical nuclear density in the plane, N(A), was used to analyze cardiomyocyte nuclei in the condition of cardiac hypertrophy caused by nitric oxide (NO) synthesis blockade and simultaneous antihypertensive treatment for 40 days (four groups of ten rats each: control, L-NAME, L-NAME+enalapril, L-NAME+verapamil). The blood pressure (BP) increased 71% in the L-NAME group. In the L-NAME+enalapril and L-NAME+verapamil groups, the BP did not show any alteration when compared with the respective controls. In comparison with the control group, nu(nu) was 250% greater, and the N(A) was 25% smaller in the L-NAME animals, while no difference occurred in the other two groups. With respect to cardiomyocyte nuclear size, the present results suggest a beneficial effect of the angiotensin-converting enzyme inhibitor enalapril and the calcium channel blocker verapamil when NO synthesis is blockaded.

Blood pressure, ventricular volume and number of cardiomyocyte nuclei in rats fed for 12 months on diets differing in fat composition

Blood pressure (BP), body mass (BM), ventricular volume (V[vent]) and the number of ventricular cardiomyocyte nuclei (N[vcn]) were analysed in rats fed different dietary fats. A total of 20 Wistar male rats were studied from 21 days old to 12 months of age and divided in the groups: soybean oil (S), canola oil (CA), lard and egg yolk (LE) and canola oil+lard and egg yolk (CA+LE). The diets had the same basal diet that included cornstarch, casein, maize, egg white and mineral and vitamin mixtures. At the moment of the sacrifice, the LE group had the greatest BP and V[vent] which was significantly higher than the other groups, and the S group had the greatest BM. The myocardial structure was apparently normal in the S and CA groups while it showed areas of diffuse interstitial fibrosis and hypertrophied cardiomyocytes in the LE group, and intramyocardial coronaries with thick tunica media and little interstitial fibrosis in CA+LE group. The N[vcn] was significantly higher in the CA group and it was lower in the LE group. These results suggest that the different dietary fats affect the myocardial structure, and the canola oil diet reduces the cardiomyocyte loss in the old rats.

Glomerular profile numerical density per area and mean glomerular volume in rats submitted to nitric oxide synthase blockade

Rats submitted to chronic inhibition of nitric oxide synthase (NOS) have developed systemic hypertension and consequent renal injury. The present study aims to determine glomerular quantitative changes due to NOS inhibition in rats. Adults and normotensive Wistar rats were separated into control and L-NAME groups (each group n=10). The animals received water and food ad libitum, while L-NAME rats received NG-Nitro-L-Arginine methyl Ester hydrochloride to inhibit NOS (50mg/kg/day) in drinking water during 40 days. After that period the rats were sacrificed, the kidneys were removed, measured, and prepared for histological and stereological analyses. The glomerular density per area [NA(glom)] and the mean glomerular volume [v] were determined per animal in 15 random fields. In L-NAME rat the blood pressure was 76% higher than the respective control group with the same age. Glomeruli had global or segmental glomerular sclerosis; some glomeruli only presented an atrophic structure. The renal volume was not different between control and L-NAME rats (p>0.05). However, L-NAME rats had the NA(glom) 33% smaller than the control rats (p=0.0001) and, concomitantly, L-NAME rats had the v (glom) 33% higher than the control ones (p=0.004). These results demonstrate morphological renal alterations caused by NOS inhibition and hypertension.

Morphological and morphometric age-related changes of the upper thoracic aorta in Leontopithecus (Lesson, 1840) (callitrichidae--primates)

Few morphologic aspects of Leontopithecus are listed in the literature, which does not provide sufficient knowledge of those simians. However, such results are important to evaluate the potential of those species as a model for studying comparative pathology. In this study, the material came from the collection of the Museu de Primatologia do Centro de Primatologia do Rio de Janeiro, fixed in 10% formalin pH 7.2. The samples were 33 individuals (five infant and five adult L. rosalia, L. chrysomelas, L. chrysopygus chrysopygus, and three adult L. chrysopygus caissara). The sections of the thoracic aorta were prepared for histological study and measurements were obtained. In the infant Leontopithecus, the aorta presents endothelial line and subendothelial space, the tunica media is not comparatively very thick. In the adults, the aorta showed enlarged tunica intima with consequent thick arterial wall, which increased with the aging process. The atheromatous plates were seen in the aortic wall of all adult L. chrysopygus chrysopygus, in two adult L. rosalia and only one adult L. chrysomelas. Differences in the aortic internal and external diameters were not significant in infants. In the adults, no significant difference was found among L. rosalia, L. chrysomelas and L. c. caissara, although the average of the aortic internal diameter in L. chrysomelas was larger than in L. c. caissara. In infant and adults L. c. chrysopygus, the thickness of the thoracic aorta is larger than in the other forms of Leontopithecus. These findings suggest a morphometric and morphologic aortic difference among the species of Leontopithecus, which could have biological significance that needs major investigation in the future.

Influence of the chronic nitric oxide synthesis inhibition on cardiomyocytes number

This work analyzes the relationship between the number of viable cells and alteration of the cardiomyocytes growth response capacity of the hypertensive rat myocardium. Hypertension was induced in Wistar rats by means of nitric oxide synthesis blockade using NG-nitro-L-arginine methyl ester (L-NAME). L-NAME (12 mg/kg per day) was given to animals in drinking water ad lib for 15 weeks. Proliferating cell nuclear antigen (PCNA) protein expression and the disector method were used to evaluate the proliferation capacity of the cardiomyocytes and its numerical density alteration (Nv[m]), respectively. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) and monoclonal antibody to single-stranded DNA were two methods that detected the process of the apoptotic cell death. The association of the p53 expression with the apoptosis was investigated using anti-p53 antibody. The heart weight, body weight, and heart weight/body weight ratio of the control rats increased 114%, 77%, and 22%, respectively, and the Nv[m] decreased 60% (P<0.0001) relative to the L-NAME rats. The cardiomyocytes did not present PCNA labeling, indicating the absence of cellular proliferation. The decline of the Nv[m] was also associated with apoptotic cell death in the myocardium of the hypertensive rats. A p53-dependent pathway seems to mediate the programmed cell death in this model of hypertension.

Effect of antihypertensive drugs on the myocardial microvessels in rats with nitric oxide blockade

In the present study, myocardial microvessels were investigated by stereology in rats with nitric oxide blockade and concomitant antihypertensive treatment for 40 days. The following five groups (10 rats each) were studied: control; L-NAME; L-NAME + spironolactone; L-NAME + enalapril; L-NAME + verapamil. The blood pressure (BP) increased every week in the L-NAME group; after an initial increase BP decreased in the treated groups and was not different from the control group. Compared to control animals, the myocardium had hypertrophied myocytes and capillary rarefaction; the tunica media and the tunica intima of small arteries were thickened, and an increase in collagen fibrils in L-NAME treated animals was noted. The enalapril, verapamil and spironolactone groups showed uniform myocardium, quite similar to the control group. The volume density of vessels, in comparison with the L-NAME group, was greater in the spironolactone group (57%), in the enalapril group (76%) and in the verapamil group (81%). The length density of vessels was, respectively, 56%, 50%, and 76% greater in the spironolactone, enalapril and verapamil groups than in the L-NAME group. The surface density of the vessels of the L-NAME group was, respectively, 88%, 96%, and 113% lower than in the spironolactone, enalapril and verapamil groups. These results are compatible with the occurrence of angiogenesis in the verapamil rats.

Stereology and immunohistochemistry of the myocardium in experimental hypertension: long-term and low-dosage administration of inhibitor of the nitric oxide synthesis

Morphological changes in the myocardium after left ventricular hypertrophy, due to chronic experimental hypertension, require an understanding of the quantitative relationship between myocyte and nonmyocyte compartments forming the structural framework of the myocardium. Hypertension was induced by long-term low-dosage inhibition of nitric oxide synthesis by NG-nitro-L-arginine methyl ester (L-NAME) in rats. L-NAME (12 mg/kg) was given to animals in water ad libitum during 15 weeks. After this period, systolic blood pressure increased almost 50% as compared with that in the control group. Morphological changes in control and L-NAME animals were investigated with stereology and immunohistochemistry. Comparing control and L-NAME animals, the surface density of myocytes decreased 73.7% while the mean cross-sectional area increased 97.6% in L-NAME rats. The volume density of myocytes decreased 45.9% and the volume density of the interstitium increased 71.7% in L-NAME rats. No stereological difference was found in blood vessels comparing the two groups. Remodeling of the cardiac interstitium occurred with increased deposition of both fibronectin and type III collagen. Fibronectin was seen in both early and latter responses to infarction while type III collagen was seen mainly in areas of incomplete healing among myocytes and around intramyocardial branches of the coronary arteries. The long-term low-dosage administration of an inhibitor of the NO synthase such as L-NAME causes myocyte hypertrophy and early interstitial and perivascular fibrosis without important quantitative changes in microcirculation.

Myofibroblast accumulation in healing rat myocardium due to long-term low-dosage nitric oxide synthesis inhibition

Inhibition of nitric oxide synthesis causes hypertension, myocardial damage and repair in rats. The myocardial healing process includes changes in extracellular matrix composition associated with the phenotypic modulation of fibroblasts. Early and later lesion areas showed a population of spindle-shaped cells expressing alpha-smooth muscle actin content. These cells apparently are associated with type III collagen and fibronectin accumulation in the ischemic lesion areas contributing to maintaining of the mechanical performance of the heart through out the healing process.

Myocardial repair with long-term and low-dose administration of a nitric oxide synthesis inhibitor. Myofibroblasts, type III collagen and fibronectin

OBJECTIVE

To study the healing process of the myocardium in hypertensive rats undergoing inhibition of nitric oxide synthesis.

METHODS

Two groups of animals were studied: one received L-NAME, 12 mg/kg/day, and the other was a control group. The presence of type III collagen, fibronectin, and alpha-smooth muscle actin-positive cells was assessed by immunohistochemistry.

RESULTS

Fibronectin was seen in both early and late lesions, while type III collagen was seen mainly in areas of incomplete healing, situated among myocytes and around the intramyocardial branches of the coronary arteries. Areas representing early and late lesions showed a population of spindle-shaped cells. Immunohistochemistry showed that these cells were positive for alpha-smooth muscle actin.

CONCLUSION

In the myocardium of hypertensive rats, the alpha-smooth muscle actin-positive cells are related to the accumulation of type III collagen and fibronectin in the areas of myocardial damage.

Numerical density of cardiac myocytes in aged rats fed a cholesterol-rich diet and a canola oil diet (n-3 fatty acid rich)

We studied the myocardium of 45 aged rats fed from 21 days after birth until 15 months of age with a standard rat diet a cholesterol-rich diet (CHO) or canola oil (O). We analysed the cardiac weight (CW) and, using unbiased stereological estimates, studied isotropic, uniform, random sections of the free left ventricular wall to determine the numerical density of the myocytes (NV[myocyte]). The CW was not statistically different between groups A and CHO: it was smallest in animals in group O (21.2% smaller in group O than in group A and 15.3% smaller in group O than in group CHO). NV[myocyte] was statistically different in all three groups and was greatest in animals in group O. By comparison with rats in group A, group CHO rats had an NV[myocyte] than was 51.3% smaller and group O, 33.3% greater. Aged rats fed with canola oil diet have a well-vascularized myocardium, which is probably associated with preservation of NV[myocyte] in the myocardium of these animals.

Stereology of the myocardium in hypertensive rats. Differences in relation to the time of inhibition of nitric oxide synthesis

Structural changes in the myocardium following inhibition of nitric oxide synthesis were studied quantitatively within two different periods. Four groups of 10 rats were studied: control and L-NAME (NG-nitro-methyl-ester-L-arginine) groups for 25 and for 40 days. L-NAME was administered at 50 mg/kg per day in the drinking water. On the 26th and 41st days, the hearts were examined. Volume densities of myocytes (Vv[m]), cardiac interstitium (Vv[int], numerical density of myocytes (Nv[m]) and mean cross-sectional area of the myocytes (A[m]) were determined. Comparing the L-NAME animals with their respective controls showed the arterial pressure (AP) and the heart weight (HW) to be increased in the L-NAME animals. At 25 days, and more obviously at 40 days, the myocytes were hypertrophied with increase of myofibrils (A[m], greater in L-NAME rats). There were some areas with ischaemic lesions, inflammatory infiltrates and perivascular and interstitial fibrosis. The intramyocardial arteries had a thick tunica media and tunica intima. At 25 days the myocardium showed no stereological difference between L-NAME and controls, but by 40 days there was decreased Vv[m] and Nv[m] and increased Vv[int] in the exposed group. Inhibition of NO synthesis provoked a time progressive myocardial change, quantified by stereology.

Stereology of the myocardium and blood biochemistry in aged rats fed with a cholesterol-rich and canola oil diet (n-3 fatty acid rich)

The myocardial changes brought about by canola oil (n-3 fatty acid rich) and hyperlipidic diets were studied in 45 rats. Three groups each consisting of 15 animals was separated into (A) which receiving a normal balanced diet; and in groups (CHO) and (O) the animals receiving hyperlipidic and canola oil diet, respectively. These diets were fed to the animals from 21 days until 15 months old, then a blood analysis was performed, after which they were sacrificed and the hearts taken for light microscopic studies. The total lipids serum was extracted and the low density lipoproteins (LDL-C and VLDL-C) and chylomicron fractions were determined as well as the cholesterol concentration in the high density lipoprotein fraction (HDL-C). The myocardium was composed of myocytes and cardiac interstitium, which is made up of connective tissue and blood vessels. The following stereological parameters were determined: a) from myocyte: volume density of myocyte, total volume of myocytes surface density of myocyte, total surface of myocyte and cross sectional area of myocyte; b) from blood vessels: volume density of blood vessels, total volume of blood vessels, length density of blood vessels, surface density of blood vessels, total surface of blood vessels and cross sectional area of vessels; c) from connective tissue: volume density of connective tissue and total volume of connective tissue. The differences were tested by the analysis of variance and Tukey test. The Mantel-Haenezel test analyzed the survival curve test comparing the different groups. Many stereological parameters had significant differences: cardiac weight, thickness of the right and left ventricular wall, aorta and pulmonary artery inner diameters. HDL-C, LDL-C, volume density of myocyte, total surface of myocyte, surface density of myocyte, total surface of myocyte, total volume of blood vessel, length density of blood vessels, surface density of blood vessels, total surface of blood vessels, volume density of connective tissue, total volume of connective tissue. Differences in survival curves were significant between groups CHO x A and CHO x O (p < 0.05) but not between groups A x O (p = 0.48). For the cardiac weight, the smallest values were found in group O. The aorta and artery pulmonary internal diameters were smaller in group CHO. The HDL-C serum was about 40% greater in group O. The LDL-C serum was more than 80% less in the same group. The average of volume density of myocyte was less in group CHO, while the average of volume density of connective tissue was greater in group CHO in comparison to groups A and O. The length density of blood vessels was greater in group O than in groups A and CHO. The surface density of myocyte and surface density of blood vessels were smaller in group CHO and greater in group A. The total surface of myocyte and total surface of blood vessels were greater in group CHO and smaller in group O. Differences were significant between groups A x CHO. The total volume of myocytes was greater in group A, while the total volume of connective tissue was greater in group CHO. The cross sectional area of myocyte and cross sectional area of vessels were greater in group CHO and smaller in group O suggesting that the canola oil diet (n-3 fatty acid rich) preserves the myocardium more than the standard and cholesterol-rich diets.

[Morphology and stereology of the myocardium in hypertensive rats. Correlation with the time of nitric oxide synthesis inhibition]

PURPOSE

To study structural changes of the myocardium in relation to the time of nitric oxide synthesis inhibition.

METHODS

Four groups of 10 rats each were studied: 2 control groups and 2 groups with administration of L-Name (50 mg/kg/day), one during 25 days and the other during 40 days. The animals were then sacrificed and the hearts were prepared for study in light microscopy, where sections strained by picro-sirius were studied with and without polarized light for analysis of the cardiac interstitium collagen. Volume densities of myocytes (Vv[m]) and interstitium (Vv[int]), the numerical density of myocytes (Nv[m]) and the mean cross-sectional area of myocytes were (A[m]) also determined.

RESULTS

The L-Name animals were compared with the respective controls. In the L-Name rats, the tail arterial pressure increased 74.5 and 90.2% in the 25 days group and in the 40 days group, respectively. The heart weight increased 50% in the 25 days group and 28.6% in the 40 days group. The myocardium of the L-Name animals presented myocyte hypertrophy with increased A(m), perivascular and interstitial fibrosis, thickness of the tunica intima and tunica media of the intramyocardial arteries. In the 40 days group the L-Name animals had decreased Vv(m) and Nv(m) and increased Vv(int).

CONCLUSIONS

Inhibition of nitric oxide synthesis provokes myocardial changes that progress with the time of L-Name administration. The stereology is useful to determine and to evaluate the myocardial changes in this model of arterial hypertension.

[Stereology of the myocardium in young and aged rats]

PURPOSE

To determine the myocardial quantitative changes comparing young and aged animals by using the stereology.

METHODS

Thirty rat hearts were studied (15 rats aged 3 months and 15 other rats aging 15 months). The hearts were removed, weighed, fixed in 10% buffered formaldehyde solution, embedded in paraffin, cut in 7 microns thick slices and stained with HE and picro-sirius stains. In each group, we counted 15 random microscopic fields. The following parameters were studied: Vv (myocyte) and Vv(interstitium)(%) (the volume densities of the cardiac myocyte and interstitium, determined by the point-counting method), and Nv(myocyte) (1/mm3) (the numerical density of the cardiac myocytes, determined with the disector method). The total number of myocytes (N[myocyte]) and the mean volume of the myocytes (V[myocytes]) were also determined. The differences were tested by the Mann-Whitney test.

RESULTS

Cardiac weight increased from 1.1 to 1.7 g, the Vv(myocyte) decreased from 76.7 to 72.2%, the Vv(interstitium) increased from 23.3 to 27.8%. The Nv(myocyte) and the N(myocyte) decreased from 14.76 x 10(4) to 6.19 x 10(4)/mm3 and 15.64 x 10(4) to 10.72 x 10(4) myocytes, respectively. Simultaneously, the V(myocyte) increased from 5.42 x 10(3) to 13.26 x 10(3) mm3. These differences were statistically significant (p < 0.05).

CONCLUSION

Myocardial changes, comparing young rats with aged ones suggest loss of myocytes (increased apoptosis?) with simultaneous myocyte hypertrophy.

Ultrastructure of the atrioventricular junctional area in the heart of Molossus molossus Pallas 1766 (Chiroptera: Molossidae)

The atrioventricular junctional area (AVJA) consists of a group of structures that connects the atrial and ventricular myocardium. Five hearts of an insect-eating bat were studied in light and transmission electron microscopy. In M. molossus, the AVJA consists in a mass of muscle fibers intermingled with variable amount of connective tissue and blood vessels surrounded by the adjacent myocardium and the attachment of the right atrioventricular and aortic valves in the fibrous skeleton. In light microscopy, conducting cells of the AV node and bundle can be distinguished from working cells: smaller size, paler staining reaction and the presence of e sheath of connective tissue surrounding each cell (largely composition by type I collagen fibers). Three cell types are observed in the AVJA. Nodal cells are irregular with few cytoplasmic organelles and several slender sarcolemmal modifications. Myofibrils are sparse and not clearly observable. Transitional cells are spindle-shaped and grouped together into bundles. The cytoplasm, poor in glycogen, has scarce electron-density and myofibrils organized into sarcomeres. Caveolae is observed randomly distributed at the periphery of the cell. The AV bundle cells are elongated with clusters of myofibrils organized in the periphery and a glycogen free area around the nucleus. Ventricular cells are bigger than the atrial ones and show well-developed myofibrils in alternated rows with mitochondria. Lipid droplets are seen near mitochondria and glycogen granules. Intercalated discs and T-tubules are found in working cells but not in conducting ones. The fibrous skeleton has collagen fibers intercalated with fibroblasts.

[The stereology of the myocardium in rats hypertensive due to the use of an inhibitor of nitric oxide synthesis]

OBJECTIVE

To study, with stereology, the myocardial changes in experimental arterial hypertension induced by chronic inhibition of nitric oxide synthesis.

MATERIAL AND METHODS

Two groups of 10 young normotensive adult rats (Wistar Strain) were studied, control and L-Name groups. In the L-Name group, the animals received 60 mg/100 ml (equivalent to 12 mg/animal) of L-Name daily in their drinking water. After 40 days, the animals were sacrificed and their hearts excised and weighed. Several myocardial fragments were taken from the free wall of the left ventricle, fixed in buffered 10% formalin and prepared for light microscopic study. Sections were stained by H-E, Gieson's Trichrome, Weigert's resorcin-fucsin and picro Sirius. Sixteen microscopic random fields were studied in each heart. The myocardium was considered to be composed of myocytes and cardiac interstitium (with blood vessels and connective tissue). Stereological parameters were volume, length and surface densities as well as the absolute values of these parameters. The differences between the animals in the control group and the L-Name group were tested with the non-parametric Mann-Whitney test.

RESULTS

The main changes in the myocardium of the L-Name group were interstitial and perivascular fibrosis and myocyte hypertrophy. In the L-Name group, blood pressure was 94.5% greater and cardiac weight 35.8% greater than in the control group (p < 0.05). The following differences were significant between the control group and the L-Name group: length, density of the blood vessels, surface densities of myocytes and blood vessels (16%, 21.2% and 40.7% smaller in the L-Name group than in the control group, respectively). The mean cross sectional area of the myocytes, the absolute volumes of the blood vessels and connective tissue were greater in the L-Name group than in the control group (41.1%, 44.6% and 38.6%, respectively). In this study, the stereological determinations for the blood vessels were smaller in the myocardium of the L-Name group than in the control group. This suggests that in L-Name myocardium hypertrophy the proliferation of blood vessels is not marked.

CONCLUSIONS

Chronic inhibition of nitric oxide synthesis significantly changes the myocardium with hypertrophy of the myocytes and fibrosis. The change in the myocardial microvasculature of the L-Name group is demonstrated by the decrease in both length and surface densities of the blood vessels.

Stereology of the myocardium in human foetuses

The rate of cellular proliferation and hypertrophy of the cardiac myocytes in the human perinatal period is still controversial. This work uses stereology to evaluate the prenatal quantitative changes of the myocardium. The hearts of 36 human foetuses, ranging from the 2nd trimester to the 3rd trimester, were studied. Fifteen random microscopic fields were analyzed in each heart. The following stereological parameters were determined: Vv[myocyte] and Vv[interstitium] (the volume densities of the cardiac myocyte and interstitium, respectively) and the Nv[myocyte] (the numerical density of the cardiac myocytes). The total number of myocytes (N[myocyte]) and the mean myocyte volume (V[myocyte]) were also determined. All differences between the second and the third trimester of gestation, tested with the Mann-Whitney test, were statistically significant (P < 0.05). The Vv[myocyte] decreased 8.69% and the Vv[interstitium] increased 49.83% in this period. Simultaneously, the Nv[myocyte] decreased 16.64%, the V[myocyte] increased 16.39%, the cardiac weight increased 366.67% and the N[myocyte] increased 272.06%. In conclusion, during the last two gestational trimesters the human heart increases in weight more than 4.5 times, the volume density of myocytes decreases while the volume density of the cardiac interstitium increases. The numerical density of myocytes per myocardium volume decreases but the myocytes became greater in mean volume (more than 16%).

[Morphological and biochemical comparison among aged rats fed with hyperlipidic and canola oil diet]

PURPOSE

To observe cardiovascular and metabolic changes due to canola oil diet (rich in n-3 fatty acid).

METHODS

Forty five rats were followed during 15 months separated in three groups. In group aged (A), they received a regular diet. In group H, animals received a hyperlipidic diet and in group O they received a canola oil diet. The rats were fed for 15 months after weaning. At the end of the experience a blood analysis was performed and heart and aorta were analyzed. The total lipids were extracted and the LDL, VLDL and HDL were determined.

RESULTS

Total cholesterol and triglyceride levels were not different among groups. Differences were found in body and cardiac weight, the thickness of the right and left ventricular wall, aorta and pulmonary diameters, HDL and LDL (p < 0.05). Smallest values of the cardiac weight and thickness of the ventricular walls were found in group O. The aorta and pulmonary internal diameters were smaller in group H. The HDL was 40% greater in group O than in groups A and H while the LDL was more than 80% lower in group O than in groups A and H. Differences in survival curves between groups H x A and between H x O were significant (p < 0.05) but not between groups A x O (p = 0.48).

CONCLUSION

Aged rats fed with canola oil diet (rich in n-3 fatty acid) presented morphological cardiovascular and metabolic changes less important in magnitude than old animals and, mainly, the same age animals under hyperlipidic diet.

[Fetal human myocardium. Proliferation of the myocytes and development of the cardiac interstitium in the last two gestational trimesters]

PURPOSE

To determine prenatal myocardial quantitative changes by using stereology.

METHODS

Twenty-six human fetuses were studied (16 in the 2nd trimester and 10 in the 3rd trimester). The hearts were dissected, weighted, fixed in the Bouin's solution for 12 h, embedded in paraplast, sectioned and stained by HE and trichrome of Gomori. Ten random microscopic fields were analyzed by heart. The following parameters were studied: Vv[myocyte] and Vv[interstitium] (%) (the volume densities of the cardiac myocyte and interstitium), and Nv[myocyte] (1/mm3) (the numerical density of the cardiac myocytes) by the dissector method. The total number of myocytes (N[myocyte]) and the mean volume of the myocytes (V[myocyte]) were also determined. The differences were tested by the Mann-Whitney non-parametric test.

RESULTS

The cardiac weight increased of 1.95 to 9.1 g, the Vv[myocyte] decreased from 85.18 to 77.78% and the Vv[interstitium] increased from 14.83 to 22.22%. The Nv[myocyte] decreased from 68.86 x 10(4) to 57.40 x 10(4)/mm3. The V[myocyte] increased from 1214.38 to 1412.31 microns3 and the N[myocyte] increased from 1.36 x 10(9) to 5.06 x 10(9) myocytes. These differences were statistically significant (p < 0.05).

CONCLUSION

These results suggest the development of the myocardium at the end of the fetal human period as being mainly hypertrophic to the myocyte and the cardiac interstitium.

Stereology of the myocardium in two species of Callithrix (Callitrichidae, primates)

The majority of studies on cardiac morphology have concentrated on Old World monkeys. Ten marmoset hearts of the genus Callithrix were studied (5 hearts of C. jacchus and 5 of C. penicillata), dissected and fixed in a 10% buffered formaldehyde solution, pH 7.2. Unbiased stereological estimates were obtained from isotropic uniform random sections of the myocardium. For stereological quantification the myocardium was regarded as consisting of cardiac myocytes and interstitium. The volume density (Vv) was determined by point counting. We used the disector method to obtain the numerical density of the cardiac myocytes (Nv[nuclei]). Myocardial stereological differences between the two species of marmoset were not statistically significant. We can therefore determine the pooled Vv[myocyte] and Nv[nuclei] as 68.6% and 41.6% (10(3)/mm3) respectively. The values found for Vv[myocyte] and Nv[nuclei] in the marmoset are respectively about 23.0 and 92.0% greater than those of the baboon, and respectively 57.3 and 45.5% greater than those in man. In contrast, the mean myocyte volume in the marmoset is not significantly different to that of man but is almost 36.0% less than that of the baboon.

Myocardial microvasculature in fetuses and neonates of rat. Stereological study

The myocardial development is anchored on the development of the blood vessels. We studied 5 fetuses in each 18.5 and 20.5 day of gestation and 5 neonates in each 2 and 7 day postnatal. Only one animal randomly selected per litter was used. Fragments of the ventricular myocardium were embedded in paraffin with random orientation, sectioned with 5 microns thickness and stained with routine methods. Myocardial capillaries were counted into the test-area and test-points were considered when falling over capillaries since these did not cut the forbidden line. The length and volume densities of the myocardial capillaries were determined (Lv[cap] and Vv[cap], respectively). The absolute length and volume of the myocardial capillaries (L[cap] and V[cap], respectively) were estimated by the product of the Lv[cap] and Vv[cap] by the volume of the heart (V[heart]). The Lv[cap] decreased greatly after birth (from 1,752.4 to 684.2/mm2). These changes were significant only between the two age groups of fetuses (days 18.5 and 20.5) and neonates of age day + 7. The Vv[cap], equal to Lv[cap], was practically unchangeable during fetal period but decreased greatly after birth. The Vv[cap] was different between early fetuses and early and late neonates. Difference was significant also between late fetuses and late neonates when the Vv[cap] decreased from 8.2 to 2.1%. Both L[cap] and V[cap] presented a tendency of increase during the fetal and neonatal periods. These absolute parameters had a significant grow-up between fetuses of age 18.5 and 20.5 days, decrease immediately after birth but improved its magnitude in late neonates. These results suggest that the relative extension and volume of the capillary bed are greater in fetal period than in early postnatal period. However, the continuous growth of the cardiac myocardium improves the absolute length and volume of the capillaries.

Cardiomyocyte proliferation and hypertrophy in the human fetus: quantitative study of the myocyte nuclei

Quantitative analyses about the cardiac growth are important today because non invasive methods of diagnosis allow in vivo study of the fetal heart. Eight human fetuses of single pregnancy were studied. The ages of the fetuses were determined according to the foot length. Four fetuses were aged in the 2nd trimester and four fetuses were aged in the 3rd trimester of gestation. We used the dissector method to obtain the volume and numerical densities of the cardiac myocytes. We studied fifteen random dissector pairs for each specimen. For reasons of efficiency, one nucleus was considered one myocyte. We counted the number of the myocyte nuclei in the test-area appearing in an unbiased counting frame of 1600 microns 2 on the one-slice plane. We determined the numerical density of myocyte nuclei (Nv[nu] 1/mm3), the volume density of the myocyte nuclei (Vv[nu]%) and the average volume of the myocyte nuclei (V[nu]micron 3). Both Vv[nu] and Nv[nu] decreased from the second to the third trimesters of gestation and these differences are significant (p = 0.03 a reduction of more than 40%). However, the V[nu] remains practically unchangeable during the last two trimesters of gestation (p > 0.05). During this period the cardiac weight increases almost 800% and, of course, we can expect that the absolute number of the myocyte nuclei increase so much. So, the increasing number of myocytes with the simultaneous decreasing of the Nv[nu] might explained by the overall growth of the myocardium. This fact explains why the unitary volume of the myocyte nuclei remains practically unchangeable during this period.

The weight of the heart in Callithrix Erxleben, 1777

The allometric relationship between the weight of the heart and the body measurements was analyzed in 31 primates of genus Callithrix (C. jacchus and C. penicillata). The data were analyzed after logarithmic transformation using the model: Ln Y = Ln a + (b) Ln X. We compared with the t-test the slopes of the males and females and the slopes of the C. Jacchus and C. penicillata. Positive allometry was found to the weight of the heart in relation to the body weight (except to females of C. penicillata = isometry) and to sitting height in females of C. jacchus and males of C. penicillata. The relationship of the weight of the heart with the sitting height was isometric in males of C. jacchus and negative in females of C. penicillata. We cannot reject the null hypothesis analyzing the differences between the slopes of males and females. Therefore, in these two species of Callithrix we accept the concept of monomorphism.

Quantitative study of the myocardium in human embryos

We studied six human embryos of the second gestational month (postsomitic period, from stages 15 to 23). They were fixed in 4% formaldehyde and serially sectioned. Stereological determinations were made from the compact layer of the ventricular myocardium: a) volume density of the myocardial parts: myocytes (Vv[myocyte]) and interstitium (Vv[interstitium]), b) numerical density of the myocytes (Nv[myocyte] mm3) calculated from six optical disector pairs per embryo, c) total number of myocytes (N[myocyte]), d) volume of the myocytes (V[myocyte] micron 3). In embryos from stages 15 to 19 the quantities of the myocytes and interstitium remained practically unchanged (no statistical difference was found). However, the volume of the ventricular myocardium mass increased more than 5 times during this period. Comparing embryos of stages 15 and 23, the mean value of the Nv[myocyte] decreased about 30 per cent, while N[myocyte] increased almost 2,000 per cent in the same period. Simultaneously, the volume of the ventricular myocardial mass increased almost 30 times, and Vv[myocyte] and Vv[interstitium] showed a small increase in the myocyte component (about 20 per cent), with a decrease of the interstitial component (about 70 per cent). In the early post-somitic period the human myocardium has a relatively small number of small myocytes, in the late post-somitic period it is composed of large and relatively abundant cardiac myocytes. The conspicuous increase in the ventricular myocardial volume observed in stage 23 seems not to be related to the increase in the interstitial portion of the myocardium. These arguments suggest both the enlargement and the division of the cardiac myocytes during the post-somitic period.

Stereology of the myocardium in embryos, fetuses and neonates of the rat

We studied with quantitative methods the myocardium of 32 specimens of rats divided into three age groups: embryos, fetuses and neonates. Days of gestation were counted from the day following an overnight mating that was considered day 1 of gestation and only one animal per litter was used. The hearts were fixed in Bouin's fixative, sectioned and stained by routine methods. Stereological determinations were made on ventricular myocardium: (1) volume density of the myocytes [Vv(myocyte)] and interstitium [Vv(interstitium)], and (2) numerical density of the myocytes [Nv(myocyte) 1/mm3] calculated from fifteen optical dissector pairs per specimen. The total number of cardiac myocytes [N(myocyte)] was calculated as the product of Nv(myocyte) and the cardiac volume. The Nv(myocyte) increased from embryos to neonates, differences between embryos and fetuses and between embryos and neonates were statistically significant. The Vv(myocyte) increased from embryos to neonates (from 80.0 to 94.0%). During this period the Vv(interstitium) decreased from 21.0 to 5.5%. Differences of the Vv(myocyte) and Vv(interstitium) were significant comparing embryos with neonates and comparing fetuses with neonates. The N(myocyte) is roughly (mean +/- standard error of the mean) 9,297 +/- 487 in fetuses and 38,438 +/- 612 in neonates. This represents an increase of about 3.1 times from fetuses to neonates while the cardiac weight increased about 2.2 times in the same period. Coefficients of error for the Nv(myocyte) estimates averaged about 7.3%, for the Vv(myocyte) estimates averaged about 1.8%, and for the Vv(interstitium) estimates averaged about 9.1%. These results suggest a high mitotic activity in the rat myocardium during prenatal life and after birth.

[Relative growth of the pancreas in the human fetus]

The relative growth of the pancreas was studied in 30 human fresh fetuses of known age (ranging from 2nd to 3rd trimesters) by using of the allometric method (Y = a X b). The weight of the pancreas (in grams) was correlated to the fetal parameters of maturity: age (in weeks), crown-rump length (in millimeters) and fetus weight (in grams). The growth of the weight of the pancreas presented positive allometry relative to gestational age and C-R length (b = 4.16 and 3.90 respectively), and light positive allometry relative to the weight of the fetuses (b = 1.15). These data are important today because non invasive methods like ultrasonography make possible to investigate the normal prenatal growth of several organs.