Coronary intercapillary distance during growth: relation to PtO2 and aerobic capacity

1976 ◽  
Vol 231 (6) ◽  
pp. 1852-1859 ◽  
Author(s):  
L Henquell ◽  
CL Odoroff ◽  
CR Honig

Intercapillary distance (ICD) was measured in left ventricles of rats beating in situ. Between 40 and 400 days of age, left ventricular weight increased threefold and ICD increased from 12.5-19.5 mum. ICD could be decreased by at least 2 mum at all ages studied. The number of capillaries which must be recruited to reduce ICD by 2 mum fell from 1,200/mm2 at 40 days to 280/mm2 at 400 days. Ventricular growth did not affect the O2 sensitivity of precapillary sphincters or the uniformity of capillary spacing. Calculations indicate that under basal conditions tissue PO2 (Pto2) in subepicardium is about the same at 40 and 400 days, even though VO2 per gram, capillary density, and ICD change twofold, twofold, and 7 mum, respectively. Nevertheless, as the ventricle grows, capillary recruitment becomes progressively less effective in defending Pto2 under conditions of stress. Diminished coronary capillary compensation for stress may, in part, account for the effect of age on the maximum aerobic capacity of the whole animal.

1991 ◽  
Vol 260 (5) ◽  
pp. H1515-H1521
Author(s):  
R. J. Torry ◽  
P. M. Connell ◽  
D. M. O'Brien ◽  
W. M. Chilian ◽  
R. J. Tomanek

Sympathetic nerves are known to influence vascular growth, but their role in coronary vascular adaptations to pressure-overload left ventricular (LV) hypertrophy is unknown. Accordingly, regional sympathectomy (SYMX) was produced by painting a ring of phenol on the posterior third of the LV in seven renal hypertensive (Page: 1 kidney, 1 wrap) and seven normotensive (sham: 1 kidney, no wrap) rabbits. Two months later, maximal myocardial blood flow (MBF) following dipyridamole-induced coronary vasodilation was determined with microspheres in the intact anterior and the sympathectomized posterior regions of conscious rabbits. Histomorphometric methods were then utilized to evaluate capillary density (CD), intercapillary distance (ICD), and volume density (VD) of subepicardial and endocardial samples of each region of perfused-fixed hearts. The Page procedure significantly increased systolic blood pressure (+29%) and LV wt/body wt (+20%) above sham rabbits. In both sham and Page groups, MBF was not significantly different between intact and sympathectomized regions within either group. SYMX did not significantly alter CD, ICD, or VD between regions in the sham animals. In contrast, SYMX significantly increased CD (+30%) and VD (+26%) and decreased ICD (-21%) in the subendocardial region of Page animals. Regional SYMX did not alter myocyte cross-sectional area in Page animals. We conclude that SYMX neither 1) significantly increases resistance vessel cross-sectional lumen area in either normal or hypertrophic hearts, nor 2) significantly influences capillary growth in normal hearts, but SYMX does 3) promote capillary growth in hearts undergoing hypertrophy in response to hypertension.


2011 ◽  
Vol 300 (5) ◽  
pp. H1863-H1874 ◽  
Author(s):  
Xin Zhou ◽  
Ji-Li Yun ◽  
Zhi-Qi Han ◽  
Fei Gao ◽  
He Li ◽  
...  

The healing process is a key determinant for postinfarction left ventricular (LV) remodeling and the development of heart failure, which could be influenced by mechanical (pressure and/or volume) load. So far, limited information exists regarding an indepth characterization of the postinfarct healing process in the mechanically unloaded state. In the present work, we performed isogenic Lewis-to-Lewis rat abdominal heterotopic heart transplantation, which is characterized by hemodynamic unloading in the left ventricle, and simultaneously ligated the left anterior descending coronary artery (T-infarct group). Pathological evolution was dynamically compared with that of in situ infarcted Lewis hearts (I-infarct group) on days 3, 7, 14, and 35. There was a remarkable myocardial salvage in the unloaded heart, as shown by the improvement in infarct size (T-infarct group: 25.47% ± 4.31% vs. I-infarct group: 38.46% ± 4.82%, P < 0.01) and the smaller fraction of fibrosis in infarct segments (T-infarct group: 42.12% ± 8.40% vs. I-infarct group: 75.65% ± 10.51%, P < 0.01). In addition, there was a progressive disorganization of the two-dimensional collagen fiber alignment as well as retarded collagen fiber maturation in the T-infarct group. We also observed enhanced angiogenesis, lymphangiogenesis, and inflammatory cell retention in the infarct region during mechanical unloading. Moreover, capillary density and collagen deposition were significantly increased in the noninfarcted area of the unloaded heart compared with the same region in the in situ infarcted heart. In conclusion, ischemic insult in the mechanically unloaded heart elicits an altered inflammatory and healing response, which is characterized by myocardial salvage, delayed resolution of inflammation, and disorganization of the collagen orientation in the infarcted region. These findings could provide novel insights into the contribution of hemodynamic load in the postinfarction healing process. Further studies are warranted to elucidate its potential mechanism.


1982 ◽  
Vol 60 (1) ◽  
pp. 23-32 ◽  
Author(s):  
B. Korecky ◽  
C. M. Hai ◽  
K. Rakusan

The subepicardial capillaries were visualised under normoxemia and hypoxemia by cinemicrophotography of the beating heart in open-chest rats. The functional intercapillary distances (ICD) were directly measured from focused frames. Under normoxemia, the average ICD was 19.2 μm and under hypoxemia, 17.9 μm (p < 0.01). This decrease of 1.3 μm under hypoxemia corresponds to an average recruitment of an additional 416 capillaries/mm2 (from 2762 to 3178).During postnatal development, both the normoxemic and hypoxemic ICD's increased with left ventricular weight. The regression analysis of this relationship indicates that the hypoxemic ICD's remain significantly shorter within the observed range.In heterotopicall y isotransplanted, empty, beating rat hearts, there was no difference in functional ICD between normoxemia and hypoxemia either in 1-day-old (18.5 versus 18.6 μm) or in 7-day-old (17.1 versus 17.1 μm) transplants.Unlike the hearts in situ which could be observed only through a long working distance, low power objective (11×), the heterotopic transplants could also be observed through a higher power (22×) lens with an optical penetration of less than 5 μm. On the same hearts almost identical ICD's were obtained by both lenses during normoxemia and hypoxemia. Therefore, recruitment of capillaries observed on the normal hearts could not be due to different optical characteristics of the hypoxemic myocardium.


Author(s):  
CL Hastings ◽  
RD Carlton ◽  
FG Lightfoot ◽  
AF Tryka

The earliest ultrastructural manifestation of hypoxic cell injury is the presence of intracellular edema. Does this intracellular edema affect the ability to cryopreserve intact myocardium? To answer this guestion, a model for anoxia induced intracellular edema (IE) was designed based on clinical intraoperative myocardial preservation protocol. The aortas of 250 gm male Sprague-Dawley rats were cannulated and a retrograde flush of Plegisol at 8°C was infused over 90 sec. The hearts were excised and placed in a 28°C bath of Lactated Ringers for 1 h. The left ventricular free wall was then sliced and the myocardium was slam frozen. Control rats (C) were anesthetized, the hearts approached by median sternotomy, and the left ventricular free wall frozen in situ immediately after slicing. The slam frozen samples were obtained utilizing the DDK PS1000, which was precooled to -185°C in liguid nitrogen. The tissue was in contact with the metal mirror for a dwell time of 20 sec, and stored in liguid nitrogen until freeze dry processing (Lightfoot, 1990).


Metabolism ◽  
1984 ◽  
Vol 33 (8) ◽  
pp. 743-749 ◽  
Author(s):  
James O. Hill ◽  
Steven B. Heymsfield ◽  
Cliff McMannus ◽  
Mario DiGirolamo

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marianna Török ◽  
Petra Merkely ◽  
Anna Monori-Kiss ◽  
Eszter Mária Horváth ◽  
Réka Eszter Sziva ◽  
...  

Abstract Background We aimed to identify sex differences in the network properties and to recognize the geometric alteration effects of long-term swim training in a rat model of exercise-induced left ventricular (LV) hypertrophy. Methods Thirty-eight Wistar rats were divided into four groups: male sedentary, female sedentary, male exercised and female exercised. After training sessions, LV morphology and function were checked by echocardiography. The geometry of the left coronary artery system was analysed on pressure-perfused, microsurgically prepared resistance artery networks using in situ video microscopy. All segments over > 80 μm in diameter were studied using divided 50-μm-long cylindrical ring units of the networks. Oxidative-nitrative (O-N) stress markers, adenosine A2A and estrogen receptor (ER) were investigated by immunohistochemistry. Results The LV mass index, ejection fraction and fractional shortening significantly increased in exercised animals. We found substantial sex differences in the coronary network in the control groups and in the swim-trained animals. Ring frequency spectra were significantly different between male and female animals in both the sedentary and trained groups. The thickness of the wall was higher in males as a result of training. There were elevations in the populations of 200- and 400-μm vessel units in males; the thinner ones developed farther and the thicker ones closer to the orifice. In females, a new population of 200- to 250-μm vessels appeared unusually close to the orifice. Conclusions Physical activity and LV hypertrophy were accompanied by a remodelling of coronary resistance artery network geometry that was different in both sexes.


Author(s):  
Katharina Lechner ◽  
Johannes Scherr ◽  
Elke Lorenz ◽  
Benjamin Lechner ◽  
Bernhard Haller ◽  
...  

Abstract Objectives To evaluate associations of omega-3 fatty acid (O3-FA) blood levels with cardiometabolic risk markers, functional capacity and cardiac function/morphology in patients with heart failure with preserved ejection fraction (HFpEF). Background O3-FA have been linked to reduced risk for HF and associated phenotypic traits in experimental/clinical studies. Methods This is a cross-sectional analysis of data from the Aldo-DHF-RCT. From 422 patients, the omega-3-index (O3I = EPA + DHA) was analyzed at baseline in n = 404 using the HS-Omega-3-Index® methodology. Patient characteristics were; 67 ± 8 years, 53% female, NYHA II/III (87/13%), ejection fraction ≥ 50%, E/e′ 7.1 ± 1.5; median NT-proBNP 158 ng/L (IQR 82–298). Pearson’s correlation coefficient and multiple linear regression analyses, using sex and age as covariates, were used to describe associations of the O3I with metabolic phenotype, functional capacity, echocardiographic markers for LVDF, and neurohumoral activation at baseline/12 months. Results The O3I was below (< 8%), within (8–11%), and higher (> 11%) than the target range in 374 (93%), 29 (7%), and 1 (0.2%) patients, respectively. Mean O3I was 5.7 ± 1.7%. The O3I was inversely associated with HbA1c (r = − 0.139, p = 0.006), triglycerides-to-HDL-C ratio (r = − 0.12, p = 0.017), triglycerides (r = − 0.117, p = 0.02), non-HDL-C (r = − 0.101, p = 0.044), body-mass-index (r = − 0.149, p = 0.003), waist circumference (r = − 0.121, p = 0.015), waist-to-height ratio (r = − 0.141, p = 0.005), and positively associated with submaximal aerobic capacity (r = 0.113, p = 0.023) and LVEF (r = 0.211, p < 0.001) at baseline. Higher O3I at baseline was predictive of submaximal aerobic capacity (β = 15.614, p < 0,001), maximal aerobic capacity (β = 0.399, p = 0.005) and LVEF (β = 0.698, p = 0.007) at 12 months. Conclusions Higher O3I was associated with a more favorable cardiometabolic risk profile and predictive of higher submaximal/maximal aerobic capacity and lower BMI/truncal adiposity in HFpEF patients. Graphic abstract Omega-3 fatty acid blood levels are inversely associated with cardiometabolic risk factors in HFpEF patients. Higher O3I was associated with a more favorable cardiometabolic risk profile and aerobic capacity (left) but did not correlate with echocardiographic markers for left ventricular diastolic function or neurohumoral activation (right). An O3I-driven intervention trial might be warranted to answer the question whether O3-FA in therapeutic doses (with the target O3I 8–11%) impact on echocardiographic markers for left ventricular diastolic function and neurohumoral activation in patients with HFpEF. This figure contains modified images from Servier Medical Art (https://smart.servier.com) licensed by a Creative Commons Attribution 3.0 Unported License.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dan Zhu ◽  
Weiyu Chen ◽  
Yuchen Pan ◽  
Tingcui Li ◽  
Ming Cui ◽  
...  

AbstractTo evaluate the effect of age and parity on maternal cardiac diastolic function in second trimester among pregnant women with normal left ventricular ejection fraction. To analyze the correlation between impaired diastolic function and pre-eclampsia. It had been suggested that maternal cardiac adaptations during pregnancy differed between nulliparous and primiparous women and also varied according to age. Impaired cardiac function may precede pre-eclampsia. Therefore, we examined the effects of parity and age on cardiac diastolic function during pregnancy and whether impaired diastolic function during the second trimester correlates with pre-eclampsia. Women with singleton pregnancies at 13 + 0 to 27 + 6 weeks’ gestation and left ventricular ejection fraction (LVEF) ≥ 50% were retrospectively identified. Diastolic function parameters were assessed using transthoracic echocardiography. Pre-eclampsia was identified from medical records. The effect of age and parity on maternal cardiac diastolic function as well as the correlation between impaired diastolic function and occurrence rate of pre-eclampsia were examined. 376 pregnant women were included (median age: 30 years; median gestational age: 14 weeks; 171 primiparous women). LVEF was 66%. Impaired cardiac diastolic function was seen in 7.8% of pregnant women < 35 years compared with 28.6% of those ≥ 35 years (p = 0.000). ROC curve showed women with maternal age over 32 began to have a higher rate of impaired cardiac diastolic function (AUC = 0.704, p = 0.000, sensitivity = 54.5%, specificity = 75.3%). There was no difference in diastolic function indices between maternal women grouped by parity. Higher maternal age was an independent risk factor of declining Em (p < 0.05). Em < 13 cm/s was significantly associated with pre-eclampsia occurrence (HR 8.56; 95% CI 3.40–21.57) after being adjusted for confounders. Maternal age is an independent risk factor for diastolic function decline. There is no difference in cardiac diastolic function between nulliparous women and primiparous women. Pre-eclampsia occurrence is significantly higher in patients with impaired diastolic function at mid-gestation. The application of risk grading using diastolic function at mid-gestation may improve the survival outcomes of pregnant women.


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