1272Effect of age, genetic background and experimental conditions on left atrial monophasic action potential duration, effective refractory period and activation time in Langendorff-perfused murine hearts

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
J Obergassel ◽  
S N Kabir ◽  
M O"reilly ◽  
L C Sommerfeld ◽  
C O"shea ◽  
...  
Keyword(s):  
Body Weight ◽  
Action Potential ◽  
Genetic Background ◽  
Left Atrial ◽  
Coronary Flow ◽  
Weight Ratio ◽  
Monophasic Action Potential ◽  
Heart Weight ◽  
Body Weight Ratio ◽  
Experimental Conditions

Abstract Funding Acknowledgements Supported by EU [CATCH ME] 633196, British Heart Foundation FS/13/43/30324, AA/18/2/34218 LF, PK, DFG FA413 LF, Studienstiftung to JO. Background Studying cardiac electrophysiology in isolated perfused beating murine hearts is a well-established method. The range of normal values for left atrial action potential durations (LA-APD), activation times (LA-AT) and effective refractory periods (atrial ERP) in murine wildtype (WT) is not well known. Purpose This study aimed to establish reference values for LA-APD, LA-AT and atrial ERP and to identify factors that influence these electrophysiological parameters in wildtype (WT) mice. Method We combined results from isolated beating heart Langendorff experiments carried out in WT between 2005 and 2019 using an octopolar catheter inserted into the right atrium and a monophasic action potential electrode recording from the LA epicardium. Electrophysiological parameters (LA-APD at 50%, 70%, 90% repolarization (APD50, APD70, APD90), LA-AT and atrial ERP) at different pacing cycle lengths (PCL) were summarized. We analyzed effects of PCL, genetic background, age, gender, heart weight to body weight ratio (HW/BW), LA weight to body weight ratio (LAW/BW) as well as coronary flow and temperature as experimental conditions. Results Electrophysiological parameters from 222 isolated hearts (114 female, mean age 6.6 ± 0.25 months, range 2.47-17.7 months) of different backgrounds (77 C57BL/6, 23 FVB/N, 33 MF1, 69 129/Sv and 20 Swiss agouti) were combined. Coronary flow rate, flow temperature and start of isolation to cannulation time were constant experimental conditions over the timespan of experiments. LA-APD was longer while LA-AT decreased with longer PCL throughout all genetic backgrounds (Figure 1A). Genetic background showed strong effects on all electrophysiological parameters. LA activation was delayed in 129/Sv compared to other backgrounds (Figure 1D). LA-APD70 and atrial ERP were significantly shorter in Swiss agouti background compared to others. LA-APD70 was also significantly prolonged in 129/Sv background compared to MF1 (Figure 1C). Atrial ERP was longer in FVB/N compared to other backgrounds. Age effects were compared in groups. Atrial ERP was significantly longer in mice ≤ 3 months compared to all older mice. Atrial ERP was also significantly prolonged (+ 3.4ms, + 13.5%) in female mice compared to males (Figure 1B). Conclusion This dataset summarizes left atrial electrophysiological parameters in the beating mouse heart and can serve as a reference for design and interpretation of electrophysiological experiments in murine models of commonly used genetic backgrounds. We confirm that cycle length, genetic background, age and gender affect atrial electrophysiological parameters. Awareness of these will support successful experimental design. Abstract Figure 1

Genetic background, sex, age and pacing cycle length affect left atrial electrophysiology in Langendorff-perfused isolated murine hearts

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
J Obergassel ◽  
M O'Reilly ◽  
C O'Shea ◽  
S.N Kabir ◽  
L.C Sommerfeld ◽  
...  
Keyword(s):  
Body Weight ◽  
Genetic Background ◽  
Left Atrial ◽  
Coronary Flow ◽  
Weight Ratio ◽  
British Heart Foundation ◽  
Funding Source ◽  
Body Weight Ratio ◽  
Experimental Conditions ◽  
Heart Foundation

Abstract Background Studying cardiac electrophysiology in isolated perfused beating murine hearts is a well-established method. The ranges of normal values for left atrial (LA) action potential durations (LA-APD), activation times (LA-AT) and effective refractory periods (atrial ERP) in murine wildtype (WT) are not well known. Purpose This study aimed to establish reference values for LA-APD, LA-AT and atrial ERP and to identify the influence of genetic background, sex and age on these electrophysiological parameters in WT mice. Method We combined results from isolated beating heart Langendorff experiments carried out in WT mice between 2005 and 2019 using an octopolar catheter inserted into the right atrium and a monophasic action potential electrode recording from the LA epicardium. Electrophysiological parameters (LA-APD at 50%, 70%, 90% repolarization (APD50, APD70, APD90), LA-AT and atrial ERP) at different pacing cycle lengths (PCL) were summarized. We analysed effects of PCL, genetic background, age, gender, heart weight to body weight ratio (HW/BW), LA weight to body weight ratio (LAW/BW) as well as coronary flow and temperature as experimental conditions. Results Electrophysiological parameters from 222 isolated hearts (114 female, mean age 6.6±0.25 months, range 2.47–17.7 months) of different backgrounds (77 C57BL/6, 23 FVB/N, 33 MF1, 69 129/Sv and 20 Swiss agouti) were combined. Coronary flow rate, flow temperature and start of isolation to cannulation time were constant experimental conditions over the timespan of experiments. LA-APD was longer while LA-AT decreased with longer PCL throughout all genetic backgrounds (Figure 1A). Genetic background showed strong effects on all electrophysiological parameters. LA-APD70 and atrial ERP were significantly shorter in Swiss agouti background compared to others. LA-APD70 was also significantly prolonged in 129/Sv background compared to MF1 (Figure 1B). LA activation was delayed in 129/Sv compared to other backgrounds (Figure 1C). Atrial ERP was longer in FVB/N compared to other backgrounds. Atrial ERP was also significantly prolonged (+ 3.4 ms, + 13.5%) in female mice compared to males (Figure 1D). Age effects were compared in groups. Atrial ERP was significantly longer in mice younger than 3 months compared to older mice (Figure 1E). Conclusion This dataset summarises left atrial electrophysiological parameters in the beating mouse heart and can serve as a reference for design and interpretation of electrophysiological experiments in murine models of commonly used genetic backgrounds. We demonstrate that PCL, genetic background, age and gender affect atrial electrophysiological parameters. Awareness of these will support successful experimental design. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): This work was partially supported by the European Commission (grant agreements no. 633196 [CATCH ME]) to LF and PK, Deutsche Forschungsgemeinschaft DFG FA413, British Heart Foundation (FS/13/43/30324 to LF and PK; AA/18/2/34218 to LF and PK).The Institute of Cardiovascular Sciences has received the British Heart Foundation (BHF) Accelerator Award (AA/18/2/34218). JO has received financial support for abroad studies within his scholarship of the Studienstiftung des deutschen Volkes (German Academic Scholarship Foundation).

Exercise conditioning increases rat myocardial calcium uptake

1986 ◽  
Vol 60 (5) ◽  
pp. 1673-1679 ◽  
Author(s):  
S. N. Levine ◽  
G. T. Kinasewitz
Keyword(s):  
Body Weight ◽  
Sarcoplasmic Reticulum ◽  
Adrenergic Receptors ◽  
Calcium Uptake ◽  
Myocardial Hypertrophy ◽  
Weight Ratio ◽  
Heart Weight ◽  
Scatchard Analysis ◽  
Body Weight Ratio ◽  
Female Wistar Rats

To investigate potential mechanisms underlying the enhanced myocardial performance consequent to exercise training, the adrenergic receptors of myocardial tissue and Ca2+ uptake into sarcoplasmic reticulum-enriched fractions from exercise conditioned animals were compared with that of sedentary controls. Female Wistar rats were exercised by swimming 30 min (5 days/wk) for 12 wk. Exercise conditioning was effective in producing myocardial hypertrophy, as reflected by an increase in heart weight (1.179 +/- 0.022 vs. 1.031 +/- 0.020 g, P less than 0.001) and heart weight-to-body weight ratio (3.29 +/- 0.06 vs. 2.77 +/- 0.05 X 10(-3), P less than 0.001) but no difference in body weight. Despite the myocardial hypertrophy, neither the affinity nor the density of the alpha 1-adrenergic receptors or the beta-adrenergic receptors determined by Scatchard analysis of the ligands [3H]prazosin and [3H]dihydroalprenolol were significantly different between the two groups. The basal Ca2+ uptake into the sarcoplasmic reticulum was also similar (9.90 +/- 0.97 vs. 9.04 +/- 0.75 nmol/mg protein/min), but the addition of calmodulin produced a significantly greater increment in Ca2+ uptake into sarcoplasmic reticulum from the exercised-conditioned animals (1.90 +/- 0.23 vs. 1.21 +/- 0.19 nmol/mg protein/min, P less than 0.03). The adenosine triphosphatase (ATPase) activities of the sarcoplasmic reticulum-enriched fractions of the two groups were similar. We conclude that exercise conditioning produces an enhancement of calmodulin-mediated calcium uptake that is independent of any effect on Ca2+-ATPase.

scholarly journals Low-intensity aerobic interval training attenuates pathological left ventricular remodeling and mitochondrial dysfunction in aortic-banded miniature swine

2010 ◽  
Vol 299 (5) ◽  
pp. H1348-H1356 ◽  
Author(s):  
Craig A. Emter ◽  
Christopher P. Baines
Keyword(s):  
Body Weight ◽  
Exercise Training ◽  
Mitochondrial Dysfunction ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Heart Weight ◽  
Lv Function ◽  
Body Weight Ratio ◽  
Miniature Swine ◽  
Low Intensity

Cardiac hypertrophy in response to hypertension or myocardial infarction is a pathological indicator associated with heart failure (HF). A central component of the remodeling process is the loss of cardiomyocytes via cell death pathways regulated by the mitochondrion. Recent evidence has indicated that exercise training can attenuate or reverse pathological remodeling, creating a physiological phenotype. The purpose of this study was to examine left ventricular (LV) function, remodeling, and cardiomyocyte mitochondrial function in aortic-banded (AB) sedentary (HFSED; n = 6), AB exercise-trained (HFTR, n = 5), and control sedentary ( n = 5) male Yucatan miniature swine. LV hypertrophy was present in both AB groups before the start of training, as indicated by increases in LV end-diastolic volume, LV end-systolic volume (LVESV), and LV end-systolic dimension (LVESD). Exercise training (15 wk) prevented further increases in LVESV and LVESD ( P < 0.05). The heart weight-to-body weight ratio, LV + septum-to-body weight ratio, LV + septum-to-right ventricle ratio, and cardiomyocyte cross-sectional area were increased in both AB groups postmortem regardless of training status. Preservation of LV function after exercise training, as indicated by the maintenance of fractional shortening, ejection fraction, and mean wall shortening and increased stroke volume, was associated with an attenuation of the increased LV fibrosis (23%) and collagen (36%) observed in HFSED animals. LV mitochondrial dysfunction, as measured by Ca2+-induced mitochondrial permeability transition, was increased in HFSED ( P < 0.05) but not HFTR animals. In conclusion, low-intensity interval exercise training preserved LV function as exemplified by an attenuation of fibrosis, maintenance of a positive inotropic state, and inhibition of mitochondrial dysfunction, providing further evidence of the therapeutic potential of exercise in a clinical setting.

scholarly journals Blocking LFA-1 Aggravates Cardiac Inflammation in Experimental Autoimmune Myocarditis

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1267 ◽  
Author(s):  
Ludwig T. Weckbach ◽  
Andreas Uhl ◽  
Felicitas Boehm ◽  
Valentina Seitelberger ◽  
Bruno C. Huber ◽  
...  
Keyword(s):  
Body Weight ◽  
Weight Ratio ◽  
Heart Weight ◽  
Lymphocyte Function ◽  
Body Weight Ratio ◽  
Antibody Treatment ◽  
Autoimmune Myocarditis ◽  
Cardiac Inflammation ◽  
Experimental Autoimmune Myocarditis ◽  
Experimental Autoimmune

The lymphocyte function-associated antigen 1 (LFA-1) is a member of the beta2-integrin family and plays a pivotal role for T cell activation and leukocyte trafficking under inflammatory conditions. Blocking LFA-1 has reduced or aggravated inflammation depending on the inflammation model. To investigate the effect of LFA-1 in myocarditis, mice with experimental autoimmune myocarditis (EAM) were treated with a function blocking anti-LFA-1 antibody from day 1 of disease until day 21, the peak of inflammation. Cardiac inflammation was evaluated by measuring infiltration of leukocytes into the inflamed cardiac tissue using histology and flow cytometry and was assessed by analysis of the heart weight/body weight ratio. LFA-1 antibody treatment severely enhanced leukocyte infiltration, in particular infiltration of CD11b+ monocytes, F4/80+ macrophages, CD4+ T cells, Ly6G+ neutrophils, and CD133+ progenitor cells at peak of inflammation which was accompanied by an increased heart weight/body weight ratio. Thus, blocking LFA-1 starting at the time of immunization severely aggravated acute cardiac inflammation in the EAM model.

Abstract 051: Growth Plasticity Of The Prenatal Murine Heart Depends On Amino Acid Availability

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Maria Hennig ◽  
Maja K Dziegelewska ◽  
Manuela Magarin ◽  
Ludwig Thierfelder ◽  
Jörg-Detlef Drenckhahn
Keyword(s):  
Body Weight ◽  
Amino Acid ◽  
Compensatory Growth ◽  
Molecular Mechanisms ◽  
Weight Ratio ◽  
Protein Diet ◽  
Heart Weight ◽  
Body Weight Ratio ◽  
Intrauterine Development ◽  
Amino Acid Availability

Intrauterine development influences the susceptibility to cardiovascular disease in adulthood, although the underlying molecular mechanisms are vastly unknown. We have recently shown that the prenatal mouse heart has an impressive regenerative capacity in response to tissue mosaicism for mitochondrial dysfunction caused by a heart specific knockout of holocytochrome c synthase (Hccs) - an X-linked gene required for mitochondrial respiration. In heterozygous Hccs knockout (Hccs+/-) embryos, hyperproliferation of healthy cardiomyocytes compensates for the functional loss of 50% of Hccs deficient cells, ensuring formation of a normally contracting heart at birth. In order to uncover molecular mechanisms enabling compensatory growth of the prenatal myocardium, we performed microarray RNA expression analyses on neonatal Hccs+/- and control hearts. These data revealed numerous genes involved in amino acid metabolism and protein homeostasis being differentially expressed in the neonatal Hccs+/- myocardium. We, therefore, hypothesized that amino acid availability is crucial for compensatory growth of Hccs+/- hearts to build a regularly sized organ and allow normal postnatal function. Thus, we studied the effects of in utero amino acid restriction on growth and development of Hccs+/- hearts by feeding dams a low protein diet (LPD) throughout pregnancy and keeping the offspring on LPD until adulthood. On standard protein diet heart weight to body weight ratio of Hccs+/- mice (n=26) born at gestational age 20.5 dpc does not differ compared to littermate controls (n=21). In contrast, Hccs+/- offspring on LPD (n=20) were found to have a significantly reduced heart weight to body weight ratio compared to control animals (n=19) at postnatal day 1. Importantly, cardiomyocyte size and proliferation were unaffected in neonatal Hccs+/- hearts on LPD, suggesting that amino acid restriction rather inhibits prenatal cardiac growth. This was in line with normal heart size and function in adult LPD Hccs+/- mice, confirming normal postnatal development. In conclusion, metabolic adaptations regulating amino acid availability might be required for growth plasticity of the fetal heart to prevent postnatal dysfunction after impaired intrauterine development.

scholarly journals STAT4 silencing underlies a novel inhibitory role of microRNA-141-3p in inflammation response of mice with experimental autoimmune myocarditis

2019 ◽  
Vol 317 (3) ◽  
pp. H531-H540 ◽  
Author(s):  
Aiqun Pan ◽  
Yuying Tan ◽  
Zhihao Wang ◽  
Guoliang Xu
Keyword(s):  
Body Weight ◽  
Cardiac Function ◽  
Weight Ratio ◽  
Heart Weight ◽  
Inflammatory Factor ◽  
Body Weight Ratio ◽  
Autoimmune Myocarditis ◽  
Experimental Autoimmune Myocarditis ◽  
Experimental Autoimmune

As an inflammatory disease afflicting the heart muscle, autoimmune myocarditis (AM) represents one of the foremost causes of heart failure. Accumulating evidence has implicated microRNAs (miRNAs) in the process of inflammation and autoimmunity. Hence, the current study aimed to investigate the mechanism by which miR-141-3p influences experimental AM (EAM). An EAM mouse model was established using 6-wk old male BALB/c mice, after which the expression of miR-141-3p and STAT4 was measured. Gain-of-function and loss-of-function investigations were performed to identify the functional role of miR-141-3p and STAT4 in EAM. Heart weight-to-body weight ratio, cardiac function, and degree of inflammation, as well as the levels of inflammation factors (IFN-γ, TNF-α, IL-2, IL-6, and IL-17) in the serum were detected. STAT4 was subsequently verified to be upregulated, and miR-141-3p was downregulated in the EAM mice. Furthermore, the overexpression of miR-141-3p or silencing of STAT4 was observed to reduce the heart weight-to-body weight ratio of EAM mice and improve cardiac function, while alleviating the degree of inflammatory cell infiltration in the myocardial tissue. Meanwhile, the overexpression of miR-141-3p was identified to diminish serum inflammatory factor levels by downregulating STAT4. Additionally, miR-141-3p could bind to STAT4 to downregulate its expression, ultimately mitigating inflammation and inducing an anti-inflammatory effect in EAM mice. Taken together, upregulation of miR-141-3p alleviates the inflammatory response in EAM mice by inhibiting STAT4, providing a promising intervention target for the molecular treatment of AM. NEW & NOTEWORTHY miR-141-3p is poorly expressed, and STAT4 is upregulated in experimental autoimmune myocarditis (EAM) mice. Overexpressing miR-141-3p inhibits EAM. miR-141-3p binds to and suppresses STAT4 expression. miR-141-3p overexpression inhibits inflammatory factors by downregulating STAT4. This study provides new insights into the treatment of autoimmune myocarditis.

Transgenic upregulation ofIK1in the mouse heart leads to multiple abnormalities of cardiac excitability

2004 ◽  
Vol 287 (6) ◽  
pp. H2790-H2802 ◽  
Author(s):  
Jingdong Li ◽  
Meredith McLerie ◽  
Anatoli N. Lopatin
Keyword(s):  
Action Potential ◽  
Ventricular Myocytes ◽  
Weight Ratio ◽  
Monophasic Action Potential ◽  
Heart Weight ◽  
Slow Phase ◽  
Mouse Heart ◽  
Premature Ventricular Contractions ◽  
Surface Ecg ◽  
Cardiac Excitability

To assess the functional significance of upregulation of the cardiac current ( IK1), we have produced and characterized the first transgenic (TG) mouse model of IK1upregulation. To increase IK1density, a pore-forming subunit of the Kir2.1 (green fluorescent protein-tagged) channel was expressed in the heart under control of the α-myosin heavy chain promoter. Two lines of TG animals were established with a high level of TG expression in all major parts of the heart: line 1 mice were characterized by 14% heart hypertrophy and a normal life span; line 2 mice displayed an increased mortality rate, and in mice ≤1 mo old, heart weight-to-body weight ratio was increased by >100%. In adult ventricular myocytes expressing the Kir2.1-GFP subunit, IK1conductance at the reversal potential was increased ∼9- and ∼10-fold in lines 1 and 2, respectively. Expression of the Kir2.1 transgene in line 2 ventricular myocytes was heterogeneous when assayed by single-cell analysis of GFP fluorescence. Surface ECG recordings in line 2 mice revealed numerous abnormalities of excitability, including slowed heart rate, premature ventricular contractions, atrioventricular block, and atrial fibrillation. Line 1 mice displayed a less severe phenotype. In both TG lines, action potential duration at 90% repolarization and monophasic action potential at 75–90% repolarization were significantly reduced, leading to neuronlike action potentials, and the slow phase of the T wave was abolished, leading to a short Q-T interval. This study provides a new TG model of IK1upregulation, confirms the significant role of IK1in cardiac excitability, and is consistent with adverse effects of IK1upregulation on cardiac electrical activity.

scholarly journals Bawei Chenxiang Wan Ameliorates Cardiac Hypertrophy by Activating AMPK/PPAR-α Signaling Pathway Improving Energy Metabolism

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaoying Zhang ◽  
Zhiying Zhang ◽  
Pengxiang Wang ◽  
Yiwei Han ◽  
Lijun Liu ◽  
...  
Keyword(s):  
Body Weight ◽  
Energy Metabolism ◽  
Cardiac Hypertrophy ◽  
Heart Function ◽  
Weight Ratio ◽  
Tibetan Medicine ◽  
Heart Weight ◽  
Cardiomyocyte Hypertrophy ◽  
Body Weight Ratio ◽  
Cross Sectional

Bawei Chenxiang Wan (BCW), a well-known traditional Chinese Tibetan medicine formula, is effective for the treatment of acute and chronic cardiovascular diseases. In the present study, we investigated the effect of BCW in cardiac hypertrophy and underlying mechanisms. The dose of 0.2, 0.4, and 0.8 g/kg BCW treated cardiac hypertrophy in SD rat model induced by isoprenaline (ISO). Our results showed that BCW (0.4 g/kg) could repress cardiac hypertrophy, indicated by macro morphology, heart weight to body weight ratio (HW/BW), left ventricle heart weight to body weight ratio (LVW/BW), hypertrophy markers, heart function, pathological structure, cross-sectional area (CSA) of myocardial cells, and the myocardial enzymes. Furthermore, we declared the mechanism of BCW anti-hypertrophy effect was associated with activating adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/peroxisome proliferator–activated receptor-α (PPAR-α) signals, which regulate carnitine palmitoyltransferase1β (CPT-1β) and glucose transport-4 (GLUT-4) to ameliorate glycolipid metabolism. Moreover, BCW also elevated mitochondrial DNA-encoded genes of NADH dehydrogenase subunit 1(ND1), cytochrome b (Cytb), and mitochondrially encoded cytochrome coxidase I (mt-co1) expression, which was associated with mitochondria function and oxidative phosphorylation. Subsequently, knocking down AMPK by siRNA significantly can reverse the anti-hypertrophy effect of BCW indicated by hypertrophy markers and cell surface of cardiomyocytes. In conclusion, BCW prevents ISO-induced cardiomyocyte hypertrophy by activating AMPK/PPAR-α to alleviate the disturbance in energy metabolism. Therefore, BCW can be used as an alternative drug for the treatment of cardiac hypertrophy.

Training and bradycardia in rats

1965 ◽  
Vol 209 (6) ◽  
pp. 1089-1094 ◽  
Author(s):  
Charles M. Tipton
Keyword(s):  
Body Weight ◽  
Weight Ratio ◽  
Experimental Period ◽  
Mature Male ◽  
Male Rats ◽  
Heart Weight ◽  
Body Weight Ratio ◽  
Satisfactory Explanation ◽  
Heart Rates ◽  
Weight Percentage

Bradycardia produced by training was investigated in 228 mature male rats belonging to normal, vagotomized, diencephalon-lesioned, immunological sympathectomized, and hypophysectomized groups. During a 70-day experimental period, resting heart rates of trained unanesthetized rats were significantly lower than those of non-trained rats at approximately 40 days after the training program had been initiated. Resting heart rates were correlated with body weight, wet and dry heart weight, percentage of solids, and the heart weight/body weight ratio (heart ratio). Several coefficients were statistically significant but the majority of the coefficients were below ±0.60 and exhibited a low relationship between the various parameters. Heart ratios for the trained vagotomized, diencephalon-lesioned, and immunological sympathectomized were significantly lower than the ratios from normal trained animals. Similar trends were observed with the nontrained subgroups when these ratios were compared with normal nontrained animals. The only exercising group that exhibited statistical evidence for cardiac hypertrophy was the normal trained group. It was concluded that other aspects beside the weight of the heart must be considered in any satisfactory explanation for this form of bradycardia.

Cardiac response of the fetal rat to carbon monoxide exposure

1983 ◽  
Vol 244 (2) ◽  
pp. H289-H297
Author(s):  
D. G. Penney ◽  
M. S. Baylerian ◽  
J. E. Thill ◽  
S. Yedavally ◽  
C. M. Fanning
Keyword(s):  
Body Weight ◽  
Weight Ratio ◽  
Placental Weight ◽  
Cardiac Response ◽  
Heart Weight ◽  
Mean Corpuscular Hemoglobin ◽  
Body Weight Ratio ◽  
Pregnant Rats ◽  
Fetal Rat ◽  
Red Blood Cell Count

Groups of pregnant rats were exposed to 200, 166, and 157 ppm CO for the last 17 out of 22 days of gestation. The number of fetuses per dam or live young per litter were unaffected. Neonatal red blood cell count was depressed, whereas mean corpuscular hemoglobin and volume were elevated. Birth weight was reduced; heart weight, heart weight-to-body weight ratio, placental weight, and placental weight-to-body weight ratio were elevated. Identical results were obtained in studies of fetuses examined daily during the final 4 days of gestation at 200 ppm. Cardiomegaly present at birth was not due to elevated myocardial water content, as dry heart weight and wet heart weight increased proportionately. Heart DNA content (microgram) was increased at both 157 and 200 ppm CO in neonates and fetuses, whereas DNA concentration (microgram/mg dry wt) was similar to the controls. Cardiac hydroxyproline concentration (microgram/mg dry wt) and content (microgram) were unaffected in neonates by fetal CO exposure at 157 and 200 ppm, although the hydroxyproline content was elevated in fetuses at 157 ppm CO. Cardiac lactate dehydrogenase (LDH) M subunit composition was elevated from 4 days before birth, until birth, at 200 ppm CO, whereas total LDH activity was unchanged. Although neonatal myocardial cytochrome c was unaltered by fetal CO exposure, myoglobin concentration (mg/g) and content (mg) were elevated. Prolonged maternal CO inhalation thus exerts significant effects on fetal body and placental weight, heart weight, enzyme constituents, and composition.

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